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9.8
Backstage developer portal has a security flaw in older versions
GHSA-928r-fm4v-mvrw
CVE-2026-29186
GHSA-928r-fm4v-mvrw
Summary
Older versions of Backstage, a tool for building developer portals, have a security issue that could allow attackers to execute unauthorized code. This issue affects versions of Backstage prior to 1.14.3. To fix the issue, update to version 1.14.3 or later.
What to do
- Update backstage plugin-techdocs-node to version 1.14.3.
- Update backstage @backstage/plugin-techdocs-node to version 1.14.3.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| backstage | plugin-techdocs-node | <= 1.14.2 | 1.14.3 |
| backstage | @backstage/plugin-techdocs-node | <= 1.14.3 | 1.14.3 |
| linuxfoundation | backstage_plugin-techdocs-node | <= 1.14.3 | – |
Original title
Backstage is an open framework for building developer portals. Prior to version 1.14.3, this is a configuration bypass vulnerability that enables arbitrary code execution. The @backstage/plugin-tec...
Original description
Backstage is an open framework for building developer portals. Prior to version 1.14.3, 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. This issue has been patched in version 1.14.3.
ghsa CVSS3.1
7.7
Vulnerability type
CWE-74
Injection
CWE-434
Unrestricted File Upload
- https://github.com/backstage/backstage/security/advisories/GHSA-928r-fm4v-mvrw
- https://backstage.io/docs/features/techdocs/architecture
- https://www.mkdocs.org/about/release-notes/#version-14-2022-09-27
- https://www.mkdocs.org/user-guide/configuration/#hooks
- https://github.com/advisories/GHSA-928r-fm4v-mvrw
- https://nvd.nist.gov/vuln/detail/CVE-2026-29186
- https://github.com/backstage/backstage Product
Published: 7 Mar 2026 · Updated: 13 Mar 2026 · First seen: 6 Mar 2026