CVE-2026-29186

@backstage/plugin-techdocs-node: TechDocs Mkdocs Configuration Key Enables Arbitrary Code Execution

State: Published
Severity: 7.7 High
Published: Mar 7, 2026
Updated: Jul 15, 2026
Reserved: Mar 4, 2026

Description

Backstage is an open framework for building developer portals. Prior to version 1.14.3, this is a configuration bypass vulnerability that enables arbitrary code execution. The @backstage/plugin-techdocs-node package uses an allowlist to filter dangerous MkDocs configuration keys during the documentation build process. A gap in this allowlist allows attackers to craft an mkdocs.yml that causes arbitrary Python code execution, completely bypassing TechDocs' security controls. This issue has been patched in version 1.14.3.

Scores

CVSS	Score	Vector	Source
3.1	7.7 High	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L	GitHub_M
3.1	9.1 Critical	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L	redhat-SADP

Weaknesses

CWE-434 Unrestricted Upload of File with Dangerous Type
CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-791 Incomplete Filtering of Special Elements

Affected Products

Product	Versions
backstagebackstage	< 1.14.3Affected

References

https://github.com/backstage/backstage/security/advisories/GHSA-928r-fm4v-mvrw
https://access.redhat.com/security/cve/CVE-2026-29186vdb-entry
RHBZ#2445480issue-tracking
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29186.json
https://access.redhat.com/errata/RHSA-2026:9742vendor-advisory
https://access.redhat.com/errata/RHSA-2026:13826vendor-advisory

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