Backstage: Remote code execution via crafted markdown_extensions in TechDocs mkdocs.yml

### Impact An authenticated user who can register catalog entities can provide a crafted `mkdocs.yml` causing arbitrary OS command execution on the TechDocs build host when the docs are built. ### Patches Patched in `@backstage/plugin-techdocs-node`, version `1.15.4`. ### Workarounds If you cannot upgrade immediately: - Switch to `techdocs.builder: external` to isolate TechDocs builds in a container. - Restrict who can register catalog entities with TechDocs annotations. - Audit existing catalog entities for suspicious `markdown_extensions` values in their `mkdocs.yml` files.

Source published

7 Oct 2026 18:03:22 UTC

Source modified

7 Oct 2026 18:15:10 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L

Publisher rating · HIGH