CVE-2026-106558

HIGH 8.8

Backstage: Improper validation of TechDocs MkDocs configuration

CVSS Score

8.8

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-502
Vendor	backstage
Product	backstage
Published	Oct 7, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

backstage / backstage

< 1.50.7 >= 1.51.0-next.0, < 1.54.9 >= 1.55.0-next.0, < 1.55.2

@backstage / plugin-techdocs-node

< 1.14.8 >= 1.15.0, < 1.15.6 >= 2.0.0, < 2.0.1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/backstage/backstage/security/advisories/GHSA-qmw3-745m-w99g github.com: https://github.com/backstage/backstage/commit/32723a0fe4e12ed80535fc65d5331765c55aa91b github.com: https://github.com/backstage/backstage/commit/944edb51c8524d3664b18f2d57ba101b1c93b709 github.com: https://github.com/backstage/backstage/commit/f18e9abcc6051491862b15e4fc60e69f8d52310c github.com: https://github.com/backstage/backstage/releases/tag/v1.50.7 github.com: https://github.com/backstage/backstage/releases/tag/v1.54.9 github.com: https://github.com/backstage/backstage/releases/tag/v1.55.2