Backstage plugin-techdocs-node: Sanitizer bypass allows code execution in TechDocs
Summary
The npm package @backstage/plugin-techdocs-node of the Backstage developer portal framework can be bypassed to circumvent the MkDocs configuration file sanitizer that was introduced to address CVE-2026-25153. A user with permission to commit changes to a repository that uses TechDocs can execute arbitrary code on the TechDocs backend host during documentation generation. The attacker needs low privileges and the victim does not need to interact; the scope change in the CVSS vector indicates impact beyond the vulnerable component.
Affected
- @backstage/plugin-techdocs-node before 1.14.6
- @backstage/plugin-techdocs-node 1.15.0 to before 1.15.4
- Backstage before 1.50.5
- Backstage 1.51.0-next.0 to before 1.54.6
Fixed in
- @backstage/plugin-techdocs-node 1.14.6 and 1.15.4
- Backstage 1.50.5 and 1.54.6
- Fix removes extra_templates from the default MkDocs key allowlist; it can only be enabled explicitly
Workaround
- Configure TechDocs with runIn: docker instead of runIn: local; this provides container isolation but does not fully mitigate the risk
- Limit repository write access to trusted parties
- Review changes to MkDocs configuration files during code review
Exploitation
- Vendor CISA SSVC assessment: exploitation none, not automatable, partial technical impact
- No public proof-of-concept or evidence of exploitation found at the time of research
Our recommendation
- Update @backstage/plugin-techdocs-node to 1.14.6 or 1.15.4, or update Backstage to 1.50.5 or 1.54.6
- Until patched, restrict commit access to TechDocs repositories and use Docker mode for TechDocs builds
- Review MkDocs configuration changes in pull requests
- Verify the CVSS score in NVD, since the sources differ from the 8.5 value in the CVE data
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-p75x-jh7p-ppcx github.com
- Backstage commit a7d995f (MkDocs configuration handling) github.com
- Backstage commit ef92d3d (fix) github.com
- Backstage release v1.50.5 github.com
- Backstage release v1.54.6 github.com
- OSV CVE-2026-106505 osv.dev
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 11:17.
Original description (NVD)
Backstage is an open framework for building developer portals. Prior to 1.14.6 and 1.15.4, the @backstage/plugin-techdocs-node package is affected by bypass of mkdocs configuration sanitizer in techdocs backend. Users with the ability to commit changes to a repository that uses TechDocs can circumvent the MkDocs configuration file sanitizer introduced in response to CVE-2026-25153 and execute arbitrary code on the TechDocs backend host during documentation generation. This issue is fixed in versions 1.14.6 and 1.15.4.
NVD references (5)
- https://github.com/backstage/backstage/commit/a7d995f11a5d27f0efbdbe8bb6c21b06988c79c9
- https://github.com/backstage/backstage/commit/ef92d3d2b76046205c580e7152956514c15640db
- https://github.com/backstage/backstage/releases/tag/v1.50.5
- https://github.com/backstage/backstage/releases/tag/v1.54.6
- https://github.com/backstage/backstage/security/advisories/GHSA-p75x-jh7p-ppcx
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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