CVE-2026-106558highCWE-502

CVE-2026-106558: high-severity vulnerability in backstage

Backstage: Improper validation of TechDocs MkDocs configuration

Published

18Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 8.8
exploitation probability
—
observed exploitation
nono source reports it
Backstage is an open framework for building developer portals. Prior to 1.14.8, 1.15.6, and 2.0.1, the @backstage/plugin-techdocs-node package improperly validated mapping-style markdown_extensions configuration. An authenticated attacker who can register or influence an SCM-backed documentation source may bypass TechDocs sanitization and cause Python objects to be imported and instantiated in the generator runtime, leading to arbitrary code execution. Earlier fixes in versions 1.14.6 and 1.15.4 did not fully address the supported mapping representation of markdown_extensions. Impact is greatest when documentation generation runs with backend credentials, filesystem access, or internal network access. This issue is fixed in versions 1.14.8, 1.15.6, and 2.0.1.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected products
@backstage · plugin-techdocs-nodebackstage · backstage
Related CVEs — backstage

In the same product, most dangerous first.

CVE-2023-35926HIGHInsecure sandbox in Backstage Scaffolder pluginEPSS 1.9%CVE-2021-41151MEDIUMPath Traversal in @backstage/plugin-scaffolder-backendEPSS 1.3%CVE-2021-32662MEDIUMTechDocs mkdocs.yml path traversalEPSS 1.3%CVE-2021-32660MEDIUMTechDocs content sanitization bypassEPSS 1.3%CVE-2021-43783HIGHPath Traversal in @backstage/plugin-scaffolder-backendEPSS 1.2%CVE-2021-32661MEDIUMTechDocs object element script injectionEPSS 1.2%
References
https://github.com/backstage/backstage/commit/32723a0fe4e12ed80535fc65d5331765c55aa91bhttps://github.com/backstage/backstage/commit/944edb51c8524d3664b18f2d57ba101b1c93b709https://github.com/backstage/backstage/commit/f18e9abcc6051491862b15e4fc60e69f8d52310chttps://github.com/backstage/backstage/releases/tag/v1.50.7https://github.com/backstage/backstage/releases/tag/v1.54.9https://github.com/backstage/backstage/releases/tag/v1.55.2https://github.com/backstage/backstage/security/advisories/GHSA-qmw3-745m-w99g