fix: add SSRF protection to LWP external entity handler#297
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The default lwp_ext_ent_handler fetched arbitrary URLs from XML external entity SYSTEM identifiers with no validation, enabling SSRF attacks against cloud metadata endpoints, internal services, and more. Changes: - Add URL scheme whitelist (only file/http/https permitted) - Add private IP/CIDR blocking for network requests (10/8, 172.16/12, 192.168/16, 169.254/16, 127/8, IPv6 ::1) - Add NoNetwork option to disable all HTTP/HTTPS fetches - file:// URIs handled locally without network round-trip - Document protections in SECURITY POD section Fixes #275 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #297 +/- ##
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+ Coverage 76.40% 76.54% +0.14%
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Files 1 1
Lines 1102 1113 +11
Branches 346 351 +5
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+ Hits 842 852 +10
Misses 52 52
- Partials 208 209 +1
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Summary
The default
lwp_ext_ent_handlerfetched arbitrary URLs from XML external entity SYSTEM identifiers with no validation, enabling SSRF attacks (cloud metadata exfiltration, internal network scanning, etc.). This adds defense-in-depth protections that are always active, plus aNoNetworkopt-in for untrusted XML.Fixes #275
Changes
file,http, andhttpsschemes permitted;gopher,ftp,data,dict, etc. are rejected before any request is made10.0.0.0/8,172.16.0.0/12,192.168.0.0/16,169.254.0.0/16(link-local/cloud metadata),127.0.0.0/8, and IPv6::1NoNetworkoption — New constructor option that disables all HTTP/HTTPS fetches while still allowing local file entity resolutionfile://optimization — file:// URIs now resolved locally without LWP round-tripTest plan
t/ssrf_protection.twith 14 tests covering:NoNetworkoption blocking http/httpsNoNetworkstill allowing local file entitiesGenerated by Kōan /fix
Quality Report
Changes: 4 files changed, 268 insertions(+), 10 deletions(-)
Code scan: clean
Tests: passed (OK)
Branch hygiene: clean
Generated by Kōan post-mission quality pipeline