# CVE-2026-106556: Backstage: Configuration bypass in TechDocs mkdocs.yml sanitization

> Authenticated users can execute arbitrary commands in the build environment by bypassing MkDocs configuration sanitization in Backstage TechDocs.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Oct 2026
- **Updated:** 7 Oct 2026
- **Also known as:** GHSA-g2hj-v2j6-vfvg

## What is CVE-2026-106556?

CVE-2026-106556 is a high-severity command injection vulnerability in Linuxfoundation Backstage, published on 7 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Backstage is an open framework for building developer portals. Prior to 1.14.6, the @backstage/plugin-techdocs-node package is affected by configuration bypass in techdocs mkdocs.yml sanitization. Insufficient validation of MkDocs configuration during TechDocs generation could allow an authenticated user who can register or modify documentation sources to execute arbitrary commands in the build environment. Impact is limited to resources accessible to the TechDocs backend or build container. This issue is fixed in versions 1.14.6 and 1.15.4.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-184 (Incomplete List of Disallowed Inputs)

## Which versions are affected by CVE-2026-106556?

It affects 2 products.


Products: Linuxfoundation Backstage, Linuxfoundation Backstage Plugin-Techdocs-Node.

## How do I fix CVE-2026-106556?

No fix has been published for CVE-2026-106556 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-106556 being exploited?

There is no known exploitation of CVE-2026-106556 in the wild and no public exploit code.

## Other vulnerabilities in Linuxfoundation Backstage

- [CVE-2026-106501](https://insights.sbomify.com/CVE-2026-106501/): Backstage: Sensitive information exposure in Scaffolder (critical 9.6)
- [CVE-2026-106558](https://insights.sbomify.com/CVE-2026-106558/): Backstage: Improper validation of TechDocs MkDocs configuration (high 8.8)
- [CVE-2026-88064](https://insights.sbomify.com/CVE-2026-88064/): Backstage: Improper input validation in TechDocs MkDocs configuration (high 8.8)
- [CVE-2026-106459](https://insights.sbomify.com/CVE-2026-106459/): Backstage: Improper input validation in Sentry scaffolder actions (high 8.5)
- [CVE-2026-106486](https://insights.sbomify.com/CVE-2026-106486/): Backstage: Improper filesystem validation in Bitbucket pull-request scaffolder actions (high 8.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-106556 and fix it if it is affected.

What it is: CVE-2026-106556 is a high-severity command injection vulnerability in Linuxfoundation Backstage, published on 7 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-106556 in the wild and no public exploit code.

Affected product: Linuxfoundation Backstage. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-106556/ (Markdown: https://insights.sbomify.com/CVE-2026-106556/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-106556
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-106556
- OSV: https://osv.dev/vulnerability/CVE-2026-106556

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-106556/
Summaries are generated and may contain mistakes; the official description above is the record.