TechDocs Mkdocs Configuration Key Enables Arbitrary Code Execution

Exploitation

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

CVSS

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

EPSS

• CVE-2026-29186: 0.87% estimated exploitation activity in the next 30 days; percentile 58.87 (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.

Impact This is a configuration bypass vulnerability that enables arbitrary code execution. The @backstage/plugin-techdocs-node package uses an allowlist to filter dangerous MkDocs configuration keys during the documentation build process. A gap in this allowlist allows attackers to craft an mkdocs.yml that causes arbitrary Python code execution, completely bypassing TechDocs' security controls. Patches Patched in @backstage/plugin-techdocs-node version 1.14.3 Workarounds If users cannot upgrade immediately: 1. Use Docker mode with restricted access: Configure TechDocs with runIn: docker instead of runIn: local. This provides container isolation, though it does not fully mitigate the risk. 2. Restrict repository access: Limit who can modify mkdocs.yml files in repositories that TechDocs processes. Only allow trusted contributors. 3. Manual review: Implement PR review requirements for changes to mkdocs.yml files to detect malicious hooks configurations before they are merged. 4.…

Published by the source

5 Mar 2026, 00:12 UTC

Last modified by the source

9 Mar 2026, 16:02 UTC

Source last checked

26 Oct 2026, 12:43 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-928r-fm4v-mvrw

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-928r-fm4v-mvrw

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# Patch Next advisory brief: CVE-2026-29186

Advisory: TechDocs Mkdocs Configuration Key Enables Arbitrary Code Execution
IDs: CVE-2026-29186, GHSA-928r-fm4v-mvrw
Record: https://patchnext.com/advisories/cve-2026-29186 (revision 2, source checked 26 Oct 2026, 12:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @backstage/plugin-techdocs-node 1.14.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @backstage/plugin-techdocs-node: affected <= 1.14.2; fixed in 1.14.3

## Suggested inspection (read-only)
- `npm ls @backstage/plugin-techdocs-node --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## 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 @backstage/plugin-techdocs-node.
- 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://osv.dev/vulnerability/GHSA-928r-fm4v-mvrw (OSV record GHSA-928r-fm4v-mvrw lists affected ranges: npm @backstage/plugin-techdocs-node >=0 <1.14.3 (fixed))
- Verified: https://github.com/advisories/GHSA-928r-fm4v-mvrw (GitHub-reviewed advisory GHSA-928r-fm4v-mvrw lists affected ranges: npm @backstage/plugin-techdocs-node >=0 <=1.14.2)

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