GHSA-f7v3-xhm6-w245 Backstage has improper input validation in TechDocs Markdown extension configuration

• npm @backstage/plugin-techdocs-node: < 1.15.4 → fixed in 1.15.4

Impact An authenticated user who can register or modify documentation sources may cause a TechDocs build to access resources outside the intended documentation boundary. Depending on deployment configuration, this may expose sensitive backend-host data or internal network resources. Patches Patched in `@backstage/plugin-techdocs-node` version `1.15.4`. Adopters must also use `pymdown-extensions` version `10.21.3` or newer, normally through `mkdocs-techdocs-core` version `1.7.0` or newer. `@backstage/plugin-techdocs-node` does not control the Python dependencies used by the generator; with an older PyMdown release, snippets may remain vulnerable to file inclusion even after their configuration is sanitized. Workarounds • Generate TechDocs only from trusted repositories with reviewed MkDocs configuration. • Use isolated build environments with restricted filesystem access and network egress. • Prefer externally generated TechDocs with appropriately sandboxed CI.