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Vulnerability · Published Oct 6, 2026 · Assigned by GitHub_M

CVE-2026-106509Backstage: Improper validation of MkDocs theme configuration in TechDocs

High 7.7

In plain English

A high-severity code injection in backstage from backstage. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.7High
Exploit odds (30 days)0.5%top 55.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

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 improper validation of mkdocs theme configuration in techdocs. When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in mkdocs.yml that cause arbitrary code execution during the documentation build process. This issue is fixed in versions 1.14.6 and 1.15.4.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npm@backstage/plugin-techdocs-node1.15.4GHSA-8w7q-29mw-gf5c

Affected products (as reported)

VendorProductVersions
backstage backstage < 1.50.5>= 1.51.0-next.0, < 1.54.6
@backstage plugin-techdocs-node < 1.14.6>= 1.15.0, < 1.15.4

Weakness: CWE-94, CWE-1336 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L

References