# Backstage: Bypass of MkDocs configuration sanitizer in TechDocs backend

Advisory record · `GHSA-p75x-jh7p-ppcx`

- **Identifiers:** `GHSA-p75x-jh7p-ppcx` · `CVE-2026-106505`
- **State:** Confirmed
- **Severity:** CVSS 7.7 High
- **Critical:** No
- **Weakness (CWE):** [CWE-426](https://cwe.mitre.org/data/definitions/426.html) · [CWE-436](https://cwe.mitre.org/data/definitions/436.html)
- **Tags:** [CWE-426](https://agentprime.io/advisories/tag/cwe-426.md) · [CWE-436](https://agentprime.io/advisories/tag/cwe-436.md)
- **Published:** 7 Oct 2026
- **Updated:** 7 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 7 Oct 2026, 16:23 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `@backstage/plugin-techdocs-node` (npm): affected `<1.15.4`; fixed in `1.15.4`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 7.7 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0031, the 24th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 13:33 UTC: First seen by agentprime
- 31 Oct 2026, 13:33 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-p75x-jh7p-ppcx)

## Sources

- [GitHub Advisory Database: GHSA-p75x-jh7p-ppcx](https://github.com/advisories/GHSA-p75x-jh7p-ppcx)
- [OSV: GHSA-p75x-jh7p-ppcx](https://osv.dev/vulnerability/GHSA-p75x-jh7p-ppcx)
- <https://github.com/backstage/backstage/security/advisories/GHSA-p75x-jh7p-ppcx>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-106505>
- <https://github.com/backstage/backstage/commit/a7d995f11a5d27f0efbdbe8bb6c21b06988c79c9>
- <https://github.com/backstage/backstage/commit/ef92d3d2b76046205c580e7152956514c15640db>
- <https://github.com/backstage/backstage>
- <https://github.com/backstage/backstage/releases/tag/v1.50.5>
- <https://github.com/backstage/backstage/releases/tag/v1.54.6>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-p75x-jh7p-ppcx>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-p75x-jh7p-ppcx/>. Everything for agents: <https://agentprime.io/llms.txt>.