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

Severity: high (CVSS 7.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-07 · updated 2026-10-13
Weakness: CWE-78

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.

Affected products

backstage: before 1.50.5; from 1.51.1 before 1.54.6; 1.51.0, 1.51.0-next0, 1.51.0-next1, 1.51.0-next2, 1.51.0-next3 — fixed in 1.50.5, 1.54.6
Linuxfoundation Backstage Plugin-Techdocs-Node: before 1.14.6; from 1.15.0 before 1.15.4 — fixed in 1.14.6, 1.15.4

How to fix

Upgrade to a fixed version: backstage 1.50.5, 1.54.6; Linuxfoundation Backstage Plugin-Techdocs-Node 1.14.6, 1.15.4. Check the vendor advisory for mitigations.

References

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