At a glance
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Actor: attacker who controls the -o/--output argument to trestle author {catalog,profile,ssp}-generate (e.g. via a CI pipeline that derives the output directory from repository-controlled data)
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Primitive: attacker-controlled --output value reaches trestle_root / args.output write sink with only is_directory_name_allowed() (parts[0]-only task-name-collision check), not the PathSecurityValidator.validate_local_path() guard added by the CVE-2026-46345 fix
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Impact: arbitrary-location file write outside the trestle workspace as the process owner (8.4 High; conservative C:N variant 7.7, still High); with --force-overwrite, the attacker-chosen directory is first recursively deleted shutil.rmtree)
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Precondition: attacker influences the -o argument in a CI/automation pipeline or multi-tenant trestle workspace running these generate subcommands
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Fix: call PathSecurityValidator.validate_local_path(markdown_path, trestle_root) immediately after building markdown_path in catalog.py, ssp.py, and prof.py, mirroring the existing jinja fix
Overview
The remediation for CVE-2026-46345 / GHSA-4q5v-7g7x-j79w ("Arbitrary File Write via Path Traversal in compliance-trestle – jinja") added a new PathSecurityValidator.validate_local_path() guard and wired it into the jinja command's output path. The identical output = trestle_root / args.output write pattern in the sibling author commands — catalog-generate, profile-generate, and ssp-generate — was not updated. Those commands instead rely on is_directory_name_allowed(), a task-name-collision check that does not stop path traversal: an absolute --output or a --output whose first component is innocuous subdir/../../../...) escapes the trestle workspace and writes generated markdown under an attacker-chosen output root outside the workspace, subject to the invoking process's filesystem permissions.
Impact
Threat model. This is not a claim that a local user harms themselves by intentionally choosing an unsafe -o. The security boundary is crossed when a trusted automation job, CI workflow, shared trestle service, or wrapper invokes one of these subcommands and derives --output from repository-controlled, tenant-controlled, or otherwise untrusted data while expecting trestle to keep generated output inside the workspace. The attacker does not need local shell access to the trestle host; they only need influence over the data that the trusted automation maps into the --output argument.
Primary claim (confirmed): Such an invocation writes control-markdown files outside the trestle workspace — arbitrary-location file write as the process owner. This is runtime-confirmed for catalog-generate: catalog-generate -o /tmp/TRESTLE_ESCAPE_ABS produced files outside the workspace on a v4.0.3 install while the same install blocked the equivalent jinja -o with a Security violation error. profile-generate and ssp-generate are source-confirmed siblings (identical trestle_root / args.output join, the same is_directory_name_allowed-only gate, no validate_local_path call); see Runtime-confirmed scope in the End-to-end verification below.
Destructive variant --force-overwrite, source-confirmed): before generating, the force-overwrite path clears the selected output directory via clear_folder(...) trestle/core/commands/common/cmd_utils.py), which performs shutil.rmtree on that directory. Because clear_folder early-returns unless the target is an existing directory, the primitive is recursive deletion of an attacker-selected directory tree outside the workspace (e.g. wiping a directory the process owner can write), not pinpoint deletion of an arbitrary single file. This is the integrity + availability impact behind I:HA:H.
Secondary (conditional) escalation: The affected population extends to every consumer that runs these generate subcommands in a CI/automation pipeline, shared/multi-tenant trestle workspace, or wrapper that forwards an externally supplied name — the same threat model GitHub/the maintainer accepted for CVE-2026-46345. Indirect code execution (e.g. overwriting a script the CI pipeline later invokes) is the bounded escalation beyond the demonstrated file-write primitive.
Technical Details
Source → Transform → Sink → Missing-guard → Result: attacker-controlled --output CLI argument → trestle_root / args.output join in catalog.pyssp.pyprof.py → CatalogAPI.write_catalog_as_markdown() writes files under the resolved path → only is_directory_name_allowed() (parts[0]-only task-name check) applied, not PathSecurityValidator.validate_local_path() → files written outside the trestle workspace.
The fix is scoped to jinja.py only
Both fix commits 247fcce…, 7d107b3…, "add path traversal protection and prevent SSTI in jinja templating") touch only trestle/core/commands/author/jinja.py (+ its tests). The new guard:
# trestle/core/commands/author/jinja.py
output_file = trestle_root / r_output_file
PathSecurityValidator.validate_local_path(output_file, trestle_root) # :229 (and :278, :297)
validate_local_path trestle/core/remote/security.py:326) is the correct guard — it .resolve()s the path and calls relative_to(trestle_root), rejecting both .. traversal and absolute paths.
The sibling generate commands were not updated
catalog-generate, profile-generate, and ssp-generate build the output path with the same join but never call validate_local_path. The only check is is_directory_name_allowed:
# trestle/core/commands/author/catalog.py:69 / ssp.py:97 / prof.py:86 (identical in all three)
if not file_utils.is_directory_name_allowed(args.output):
raise TrestleError(f'{args.output} is not an allowed directory name')
...
markdown_path = trestle_root / args.output # catalog.py:90 / prof.py:110 (var markdown_path); ssp.py:111 (var md_path) — same joinis_directory_name_allowed trestle/common/file_utils.py:95) was designed to stop task names that collide with OSCAL model directories, not traversal. It inspects only parts[0]:
def is_directory_name_allowed(name: str) -> bool:
pathed_name = pathlib.Path(name)
root_path = pathed_name.parts[0]
if root_path in const.MODEL_TYPE_TO_MODEL_DIR.values(): return False # blocks "catalogs", "profiles", ...
if root_path[0] == '.': return False # blocks leading "." (i.e. "../x")
if pathed_name.suffix != '': return False # blocks names with a file suffix
if '__global__' in pathed_name.parts: return False
return TrueTwo payloads defeat it:
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Absolute path — --output /tmp/pwned. parts[0] is / (not an OSCAL dir, not .-prefixed, no suffix) → allowed. trestle_root / '/tmp/pwned' collapses to /tmp/pwned (pathlib discards the left operand on absolute join).
-
Non-leading .. — --output subdir/../../../../../../tmp/pwned. parts[0] is subdir (innocuous) → allowed. The .. segments resolve out of the workspace at write time.
The validated value flows unchanged to the write sink with no further sanitisation grep for resolve()/relative_to/validate_local_path across the catalog write path returns zero hits): ControlContext.generate(..., md_root=markdown_path, ...) stores it as a dataclass field trestle/core/control_context.py:46) and CatalogAPI.write_catalog_as_markdown() calls self._context.md_root.mkdir(exist_ok=True, parents=True) trestle/core/catalog/catalog_api.py:72) then writes .md files under it.
Additional unguarded siblings create, replicate)
trestle create trestle/core/commands/create.py:95, desired_model_dir = trestle_root / plural_path / args.output) and trestle replicate replicate.py:90) have no is_directory_name_allowed check at all and accept the same absolute / .. --output. They write a structured OSCAL model file and refuse to overwrite an existing target .exists() raises), so the primitive is create-only there — lower impact than the generate commands, but the same missing-guard root cause. These are flagged as related defense-in-depth sinks sharing the root cause, not as the primary impact claim of this report.
Severity note
Metrics mirror the parent CVE-2026-46345 (8.4, AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H). I:HA:H are direct and demonstrated: out-of-workspace file creation, plus recursive shutil.rmtree of an attacker-chosen directory under --force-overwrite. C:H is proposed for consistency with the parent advisory's published score for the same out-of-workspace write boundary; however, the directly demonstrated primitive is write/overwrite rather than file read, so a conservative vector with C:N AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H) yields 7.7, still High. S:U because trestle writes as the invoking user.
Why OSCAL id-validation does not prevent this
OSCAL model ids control.id, group.id) are NCName-validated constr(regex=…)) and cannot contain /, , or a leading .., so the per-control leaf filenames grp1/ac-1.md) cannot themselves traverse. That validation does not help here: the base output root md_root = trestle_root / args.output is built from the raw, unconstrained -o/--output CLI string and is joined before those safe leaves. An absolute or non-leading.. -o escapes the workspace, and the NCName-safe leaves are written underneath the escaped root — confirmed by the PoC, where the escape occurs at md_root /tmp/TRESTLE_ESCAPE_ABS) with grp1/ac-1.md written beneath it.
Reproduction
Non-web target (Python CLI). PoC is a command sequence run against a local install of the project's current source (HEAD e22e35b, reports as v4.0.3) — no vendor infrastructure touched.
Step 1 — Set up a normal trestle workspace with a one-control catalog
pip install -e . # editable install of the affected source (v4.0.3)
mkdir /tmp/poc_ws && cd /tmp/poc_ws
trestle init
mkdir -p catalogs/mycat
python3 - <<'PY'
import uuid, json
cat = {"catalog":{"uuid":str(uuid.uuid4()),
"metadata":{"title":"PoC Catalog","last-modified":"2026-01-01T00:00:00.000+00:00","version":"1.0","oscal-version":"1.0.4"},
"groups":[{"id":"grp1","title":"Group One","controls":[
{"id":"ac-1","title":"PoC Control","parts":[{"id":"ac-1_smt","name":"statement","prose":"PoC statement prose."}]}]}]}}
json.dump(cat, open("catalogs/mycat/catalog.json","w"), indent=2)
PYStep 2 — Trigger the boundary failure (absolute-path escape)
trestle author catalog-generate -n mycat -o /tmp/TRESTLE_ESCAPE_ABS
ls /tmp/TRESTLE_ESCAPE_ABS/grp1/ac-1.md
Recorded output:
$ ls /tmp/TRESTLE_ESCAPE_ABS/grp1/ac-1.md
/tmp/TRESTLE_ESCAPE_ABS/grp1/ac-1.md # written OUTSIDE /tmp/poc_ws
$ head -3 /tmp/TRESTLE_ESCAPE_ABS/grp1/ac-1.md
# ac-1 - \[Group One\] PoC Control
## Control Statement
Step 3 — Same escape via non-leading .. (defeats is_directory_name_allowed)
trestle author catalog-generate -n mycat -o 'subdir/../../../../../../tmp/TRESTLE_ESCAPE_DOTDOT'
ls /tmp/TRESTLE_ESCAPE_DOTDOT/grp1/ac-1.md # -> exists, outside the workspace
Step 4 — Differential: the patched jinja -o is blocked on the SAME install
echo 'hello {{ 1+1 }}' > template.j2
trestle author jinja -i template.j2 -o '/tmp/TRESTLE_JINJA_BLOCKED'Recorded output (fix is active; proves this is an incomplete fix, not an unpatched version):
ERROR: ... Security violation: Path traversal blocked. Attempted to access
"/tmp/TRESTLE_JINJA_BLOCKED" which is outside the trestle workspace "/tmp/poc_ws"
# (no file created)
catalog-generate escapes while jinja is blocked → the validate_local_path remediation was never applied to the generate commands.
End-to-end verification (runtime)
-
Lab setup: editable install pip install -e .) of the affected source at HEAD e22e35b (reports as v4.0.3, the release that contains the GHSA-4q5v jinja fix). import trestle.core.commands.author.catalog resolves to the in-tree source file, confirming the run exercises HEAD, not a stale wheel.
-
Observed end-to-end effect (not an intermediate return value): files physically written outside the workspace — /tmp/TRESTLE_ESCAPE_ABS/grp1/ac-1.md and /tmp/TRESTLE_ESCAPE_DOTDOT/grp1/ac-1.md — while /tmp/poc_ws (the trestle root) contained no such directory. Confirmed by findls.
-
Differential control: the same install rejects the equivalent jinja -o with Security violation: Path traversal blocked … outside the trestle workspace, writing nothing. The guard exists and works in jinja; it is simply absent from the generate commands.
-
Guard bypass, isolated: importing is_directory_name_allowed semantics and joining via pathlib confirms -o /tmp/pwned (absolute) and -o subdir/../../../tmp/pwned (innocuous leading component) both pass the check and resolve outside the root, while the naive -o ../../tmp/pwned is the only form the check stops.
-
Runtime-confirmed scope (what was executed vs source-confirmed): the write escape is runtime-confirmed for catalog-generate (Steps 2–4 above). profile-generate and ssp-generate are source-confirmed siblings — same trestle_root / args.output join prof.py:110, ssp.py:111), same is_directory_name_allowed-only gate prof.py:86, ssp.py:97), no validate_local_path — and should be fixed in the same patch. The --force-overwrite recursive-delete primitive clear_folder → shutil.rmtree, with an early return unless the target is an existing directory) is source-confirmed; the PoC above exercises the write escape, not -fo.
Suggested Fix
Root-cause fix: Mirror the jinja fix in the three generate commands (and, for completeness, createreplicate): after constructing the output path, call the existing guard before any mkdir/write.
# catalog.py / ssp.py / prof.py, immediately after markdown_path = trestle_root / args.output
from trestle.core.remote.security import PathSecurityValidator
PathSecurityValidator.validate_local_path(markdown_path, trestle_root)
is_directory_name_allowed() should be retained for its original purpose (OSCAL-dir-collision prevention) but must not be relied on for traversal defence.
Defense-in-depth: Harden is_directory_name_allowed to reject absolute paths pathed_name.is_absolute()) and any .. component so it provides a secondary layer even if the primary validate_local_path call is accidentally omitted in future.
References
Yanchon918s Reporter
At a glance
Actor: attacker who controls the -o/--output argument to trestle author {catalog,profile,ssp}-generate (e.g. via a CI pipeline that derives the output directory from repository-controlled data)
Primitive: attacker-controlled --output value reaches trestle_root / args.output write sink with only is_directory_name_allowed() (parts[0]-only task-name-collision check), not the PathSecurityValidator.validate_local_path() guard added by the CVE-2026-46345 fix
Impact: arbitrary-location file write outside the trestle workspace as the process owner (8.4 High; conservative C:N variant 7.7, still High); with --force-overwrite, the attacker-chosen directory is first recursively deleted shutil.rmtree)
Precondition: attacker influences the -o argument in a CI/automation pipeline or multi-tenant trestle workspace running these generate subcommands
Fix: call PathSecurityValidator.validate_local_path(markdown_path, trestle_root) immediately after building markdown_path in catalog.py, ssp.py, and prof.py, mirroring the existing jinja fix
Overview
The remediation for CVE-2026-46345 / GHSA-4q5v-7g7x-j79w ("Arbitrary File Write via Path Traversal in compliance-trestle – jinja") added a new PathSecurityValidator.validate_local_path() guard and wired it into the jinja command's output path. The identical output = trestle_root / args.output write pattern in the sibling author commands — catalog-generate, profile-generate, and ssp-generate — was not updated. Those commands instead rely on is_directory_name_allowed(), a task-name-collision check that does not stop path traversal: an absolute --output or a --output whose first component is innocuous subdir/../../../...) escapes the trestle workspace and writes generated markdown under an attacker-chosen output root outside the workspace, subject to the invoking process's filesystem permissions.
Impact
Threat model. This is not a claim that a local user harms themselves by intentionally choosing an unsafe -o. The security boundary is crossed when a trusted automation job, CI workflow, shared trestle service, or wrapper invokes one of these subcommands and derives --output from repository-controlled, tenant-controlled, or otherwise untrusted data while expecting trestle to keep generated output inside the workspace. The attacker does not need local shell access to the trestle host; they only need influence over the data that the trusted automation maps into the --output argument.
Primary claim (confirmed): Such an invocation writes control-markdown files outside the trestle workspace — arbitrary-location file write as the process owner. This is runtime-confirmed for catalog-generate: catalog-generate -o /tmp/TRESTLE_ESCAPE_ABS produced files outside the workspace on a v4.0.3 install while the same install blocked the equivalent jinja -o with a Security violation error. profile-generate and ssp-generate are source-confirmed siblings (identical trestle_root / args.output join, the same is_directory_name_allowed-only gate, no validate_local_path call); see Runtime-confirmed scope in the End-to-end verification below.
Destructive variant --force-overwrite, source-confirmed): before generating, the force-overwrite path clears the selected output directory via clear_folder(...) trestle/core/commands/common/cmd_utils.py), which performs shutil.rmtree on that directory. Because clear_folder early-returns unless the target is an existing directory, the primitive is recursive deletion of an attacker-selected directory tree outside the workspace (e.g. wiping a directory the process owner can write), not pinpoint deletion of an arbitrary single file. This is the integrity + availability impact behind I:HA:H.
Secondary (conditional) escalation: The affected population extends to every consumer that runs these generate subcommands in a CI/automation pipeline, shared/multi-tenant trestle workspace, or wrapper that forwards an externally supplied name — the same threat model GitHub/the maintainer accepted for CVE-2026-46345. Indirect code execution (e.g. overwriting a script the CI pipeline later invokes) is the bounded escalation beyond the demonstrated file-write primitive.
Technical Details
Source → Transform → Sink → Missing-guard → Result: attacker-controlled --output CLI argument → trestle_root / args.output join in catalog.pyssp.pyprof.py → CatalogAPI.write_catalog_as_markdown() writes files under the resolved path → only is_directory_name_allowed() (parts[0]-only task-name check) applied, not PathSecurityValidator.validate_local_path() → files written outside the trestle workspace.
The fix is scoped to jinja.py only
Both fix commits 247fcce…, 7d107b3…, "add path traversal protection and prevent SSTI in jinja templating") touch only trestle/core/commands/author/jinja.py (+ its tests). The new guard:
validate_local_path trestle/core/remote/security.py:326) is the correct guard — it .resolve()s the path and calls relative_to(trestle_root), rejecting both .. traversal and absolute paths.
The sibling generate commands were not updated
catalog-generate, profile-generate, and ssp-generate build the output path with the same join but never call validate_local_path. The only check is is_directory_name_allowed:
is_directory_name_allowed trestle/common/file_utils.py:95) was designed to stop task names that collide with OSCAL model directories, not traversal. It inspects only parts[0]:
Two payloads defeat it:
Absolute path — --output /tmp/pwned. parts[0] is / (not an OSCAL dir, not .-prefixed, no suffix) → allowed. trestle_root / '/tmp/pwned' collapses to /tmp/pwned (pathlib discards the left operand on absolute join).
Non-leading .. — --output subdir/../../../../../../tmp/pwned. parts[0] is subdir (innocuous) → allowed. The .. segments resolve out of the workspace at write time.
The validated value flows unchanged to the write sink with no further sanitisation grep for resolve()/relative_to/validate_local_path across the catalog write path returns zero hits): ControlContext.generate(..., md_root=markdown_path, ...) stores it as a dataclass field trestle/core/control_context.py:46) and CatalogAPI.write_catalog_as_markdown() calls self._context.md_root.mkdir(exist_ok=True, parents=True) trestle/core/catalog/catalog_api.py:72) then writes .md files under it.
Additional unguarded siblings create, replicate)
trestle create trestle/core/commands/create.py:95, desired_model_dir = trestle_root / plural_path / args.output) and trestle replicate replicate.py:90) have no is_directory_name_allowed check at all and accept the same absolute / .. --output. They write a structured OSCAL model file and refuse to overwrite an existing target .exists() raises), so the primitive is create-only there — lower impact than the generate commands, but the same missing-guard root cause. These are flagged as related defense-in-depth sinks sharing the root cause, not as the primary impact claim of this report.
Severity note
Metrics mirror the parent CVE-2026-46345 (8.4, AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H). I:HA:H are direct and demonstrated: out-of-workspace file creation, plus recursive shutil.rmtree of an attacker-chosen directory under --force-overwrite. C:H is proposed for consistency with the parent advisory's published score for the same out-of-workspace write boundary; however, the directly demonstrated primitive is write/overwrite rather than file read, so a conservative vector with C:N AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H) yields 7.7, still High. S:U because trestle writes as the invoking user.
Why OSCAL id-validation does not prevent this
OSCAL model ids control.id, group.id) are NCName-validated constr(regex=…)) and cannot contain /, , or a leading .., so the per-control leaf filenames grp1/ac-1.md) cannot themselves traverse. That validation does not help here: the base output root md_root = trestle_root / args.output is built from the raw, unconstrained -o/--output CLI string and is joined before those safe leaves. An absolute or non-leading.. -o escapes the workspace, and the NCName-safe leaves are written underneath the escaped root — confirmed by the PoC, where the escape occurs at md_root /tmp/TRESTLE_ESCAPE_ABS) with grp1/ac-1.md written beneath it.
Reproduction
Non-web target (Python CLI). PoC is a command sequence run against a local install of the project's current source (HEAD e22e35b, reports as v4.0.3) — no vendor infrastructure touched.
Step 1 — Set up a normal trestle workspace with a one-control catalog
Step 2 — Trigger the boundary failure (absolute-path escape)
Recorded output:
Step 3 — Same escape via non-leading .. (defeats is_directory_name_allowed)
Step 4 — Differential: the patched jinja -o is blocked on the SAME install
Recorded output (fix is active; proves this is an incomplete fix, not an unpatched version):
catalog-generate escapes while jinja is blocked → the validate_local_path remediation was never applied to the generate commands.
End-to-end verification (runtime)
Lab setup: editable install pip install -e .) of the affected source at HEAD e22e35b (reports as v4.0.3, the release that contains the GHSA-4q5v jinja fix). import trestle.core.commands.author.catalog resolves to the in-tree source file, confirming the run exercises HEAD, not a stale wheel.
Observed end-to-end effect (not an intermediate return value): files physically written outside the workspace — /tmp/TRESTLE_ESCAPE_ABS/grp1/ac-1.md and /tmp/TRESTLE_ESCAPE_DOTDOT/grp1/ac-1.md — while /tmp/poc_ws (the trestle root) contained no such directory. Confirmed by findls.
Differential control: the same install rejects the equivalent jinja -o with Security violation: Path traversal blocked … outside the trestle workspace, writing nothing. The guard exists and works in jinja; it is simply absent from the generate commands.
Guard bypass, isolated: importing is_directory_name_allowed semantics and joining via pathlib confirms -o /tmp/pwned (absolute) and -o subdir/../../../tmp/pwned (innocuous leading component) both pass the check and resolve outside the root, while the naive -o ../../tmp/pwned is the only form the check stops.
Runtime-confirmed scope (what was executed vs source-confirmed): the write escape is runtime-confirmed for catalog-generate (Steps 2–4 above). profile-generate and ssp-generate are source-confirmed siblings — same trestle_root / args.output join prof.py:110, ssp.py:111), same is_directory_name_allowed-only gate prof.py:86, ssp.py:97), no validate_local_path — and should be fixed in the same patch. The --force-overwrite recursive-delete primitive clear_folder → shutil.rmtree, with an early return unless the target is an existing directory) is source-confirmed; the PoC above exercises the write escape, not -fo.
Suggested Fix
Root-cause fix: Mirror the jinja fix in the three generate commands (and, for completeness, createreplicate): after constructing the output path, call the existing guard before any mkdir/write.
is_directory_name_allowed() should be retained for its original purpose (OSCAL-dir-collision prevention) but must not be relied on for traversal defence.
Defense-in-depth: Harden is_directory_name_allowed to reject absolute paths pathed_name.is_absolute()) and any .. component so it provides a secondary layer even if the primary validate_local_path call is accidentally omitted in future.
References
Vendor security policy: https://github.com/oscal-compass/compliance-trestle/security/policy
Submission endpoint: https://github.com/oscal-compass/compliance-trestle/security/advisories/new
Parent advisory (incompletely fixed): GHSA-4q5v-7g7x-j79w / CVE-2026-46345 — "Arbitrary File Write via Path Traversal in compliance-trestle – jinja"
Coordinated disclosure batch (part of the same PathSecurityValidator remediation): GHSA-gg2g-p7xc-qqmm (SSTI RCE), GHSA-g3vg-vx23-3858 (cache path traversal), GHSA-mj4x-vf5c-5xg8 (profile-import path traversal read), GHSA-w76h-q7c6-jpjp (SSRF)
Fix commits (jinja-only scope): 247fcce, 7d107b3
Affected sinks: trestle/core/commands/author/catalog.py:69,90; author/ssp.py:97,111; author/prof.py:86,110; bypassed guard trestle/common/file_utils.py:95; write sink trestle/core/catalog/catalog_api.py:72; unused-here correct guard trestle/core/remote/security.py:326
Additional unguarded siblings: trestle/core/commands/create.py:95, trestle/core/commands/replicate.py:90