Backstage: Improper validation of MkDocs theme configuration in TechDocs
### Impact When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in `mkdocs.yml` that cause arbitrary code execution during the documentation build process. ### Patches Patched in `@backstage/plugin-techdocs-node` version `1.15.4` ### Workarounds - Configure TechDocs with `techdocs.generator.runIn: 'docker'` instead of `'local'` to provide container isolation, though this does not fully mitigate the risk. - Restrict write access to repositories registered in the Backstage catalog to trusted users.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-106509US | high8.8 | — | ||
Backstage is an open framework for building developer portals. Prior to 1.14.6, the @backstage/plugin-techdocs-node package is affected by improper validation of mkdocs theme confi… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/backstage/backstagePACKAGE
- https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbbWEB
- https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9dWEB
- https://github.com/backstage/backstage/releases/tag/v1.50.5WEB
- https://github.com/backstage/backstage/releases/tag/v1.54.6WEB
- https://github.com/backstage/backstage/security/advisories/GHSA-8w7q-29mw-gf5cWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-106509ADVISORY
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