Backstage has improper input validation in TechDocs Markdown extension configuration

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-106557: 0.38% estimated exploitation activity in the next 30 days; percentile 31.51 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

7 Oct 2026, 16:22 UTC

Last modified by the source

7 Oct 2026, 16:30 UTC

Source last checked

26 Oct 2026, 13:07 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-f7v3-xhm6-w245

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-f7v3-xhm6-w245

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-f7v3-xhm6-w245

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-106557

Advisory: Backstage has improper input validation in TechDocs Markdown extension configuration
IDs: CVE-2026-106557, GHSA-f7v3-xhm6-w245
Record: https://patchnext.com/advisories/cve-2026-106557 (revision 3, source checked 26 Oct 2026, 13:07 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @backstage/plugin-techdocs-node 1.15.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @backstage/plugin-techdocs-node: affected < 1.15.4; fixed in 1.15.4

## Suggested inspection (read-only)
- `npm ls @backstage/plugin-techdocs-node --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @backstage/plugin-techdocs-node.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f7v3-xhm6-w245 (GitHub-reviewed advisory GHSA-f7v3-xhm6-w245 lists affected ranges: npm @backstage/plugin-techdocs-node >=0 <1.15.4)
- Verified: https://osv.dev/vulnerability/GHSA-f7v3-xhm6-w245 (OSV record GHSA-f7v3-xhm6-w245 lists affected ranges: npm @backstage/plugin-techdocs-node >=0 <1.15.4 (fixed))

Commands are suggestions: review each one before running it.