Gogs: Stored XSS via data URI in issue comments

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.7 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

EPSS

• CVE-2026-26022: 0.35% estimated exploitation activity in the next 30 days; percentile 29.14 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A Stored Cross-site Scripting (XSS) vulnerability exists in the comment and issue description functionality. The application's HTML sanitizer explicitly allows data: URI schemes, enabling authenticated users to inject arbitrary JavaScript execution via malicious links. Details The vulnerability is located in internal/markup/sanitizer.go. The application uses the bluemonday HTML sanitizer but explicitly weakens the security policy by allowing the data URL scheme: While the Markdown renderer rewrites relative links (mitigating standard Markdown link attacks), Gogs supports Raw HTML input. Raw HTML anchor tags bypass the Markdown parser's link rewriting and are processed directly by the sanitizer. Since the sanitizer is configured to allow data: URIs, payloads like <a href="data:text/html..." are rendered as-is. PoC 1. Create a file named exploit.md in a repository. 2. Add the following content (Raw HTML): 3. Commit and push the file. 4. Navigate to the file in the Gogs web…

Published by the source

5 Mar 2026, 19:26 UTC

Last modified by the source

5 Mar 2026, 22:28 UTC

Source last checked

26 Oct 2026, 15:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xrcr-gmf5-2r8j

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-26022

Advisory: Gogs: Stored XSS via data URI in issue comments
IDs: CVE-2026-26022, GHSA-xrcr-gmf5-2r8j
Record: https://patchnext.com/advisories/cve-2026-26022 (revision 1, source checked 26 Oct 2026, 15:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: gogs.io/gogs 0.14.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go gogs.io/gogs: affected <= 0.14.1; fixed in 0.14.2

## Suggested inspection (read-only)
- Go gogs.io/gogs: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on gogs.io/gogs.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-xrcr-gmf5-2r8j (GitHub-reviewed advisory GHSA-xrcr-gmf5-2r8j lists affected ranges: Go gogs.io/gogs >=0 <=0.14.1)

Commands are suggestions: review each one before running it.