CVE-2026-113429
Deferred Deferred - Pending Action

Stored XSS in Gitea Actions Artifact Download

Publication date: 2026-11-01

Last updated on: 2026-11-01

Assigner: Gitea Limited

Description
Legacy (v1 to v3) Actions artifact uploads stored the request's `Content-Encoding` header unchecked in the column that is served as the artifact's `Content-Type` on download, and a value starting with `video/` or `audio/` also removed the sandboxing Content-Security-Policy. A user who can run an Actions job could upload an artifact that a browser renders as HTML on the Gitea origin when the direct artifact download URL is opened, and the URL is reachable anonymously on public repositories. A victim who opens the link runs the attacker's script with their own session, which for an administrator means control of the instance. Legacy uploads now store only the `gzip` marker, and the special serve headers are chosen only for valid media types.

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Meta Information

Published
2026-11-01
Last Modified
2026-11-01
Generated
2026-11-01
AI Q&A
2026-11-01
EPSS Evaluated
N/A
NVD
CVE-2026-113429

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
Gitea Gitea 0

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This vulnerability involves Gitea's legacy artifact upload system storing the Content-Encoding header unchecked, which is later used as the Content-Type when downloading artifacts. Attackers can manipulate this to serve HTML content with a video/audio MIME type, bypassing Content-Security-Policy sandboxing. This allows stored cross-site scripting (XSS) attacks where malicious scripts execute in a victim's session.

Detection Guidance

Check Gitea version for vulnerability exposure. Run: gitea --version. If version is below 28.3.0 or 29.0.0, the system is vulnerable. Inspect artifact uploads for Content-Encoding headers starting with video/ or audio/. Review server logs for suspicious artifact downloads with HTML content types.

Impact Analysis

If you are a Gitea user with Actions job permissions, an attacker could upload a malicious artifact. Opening the artifact download link in a browser may execute the attacker's script in your session. For administrators, this could lead to full instance compromise. Regular users may face session hijacking or data theft.

Compliance Impact

This vulnerability could lead to stored cross-site scripting (XSS) attacks, potentially allowing unauthorized access to sensitive data. For GDPR, this may result in unauthorized data processing or breaches. For HIPAA, it could expose protected health information if an attacker gains administrative control of the Gitea instance.

Mitigation Strategies

Upgrade Gitea to version 28.3.0 or 29.0.0 immediately. Disable legacy artifact uploads if possible. Restrict Actions permissions to trusted users only. Monitor for unauthorized artifact uploads and review CSP headers for artifacts.

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