Backstage up to 1.14.5/1.15.3 TechDocs backend mkdocs.yml input validation

Summaryinfo

A vulnerability was found in Backstage up to 1.14.5/1.15.3. It has been declared as critical. The affected element is an unknown function of the file mkdocs.yml of the component TechDocs backend. Such manipulation leads to input validation. This vulnerability is referenced as CVE-2026-88064. It is possible to launch the attack remotely. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Backstage up to 1.14.5/1.15.3 and classified as critical. Affected by this issue is some unknown processing of the file mkdocs.yml of the component TechDocs backend. The manipulation with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Backstage is an open framework for building developer portals. Prior to 1.14.6 and from 1.15.0 until 1.15.4, the @backstage/plugin-techdocs-node package insufficiently validates mkdocs.yml supplied by an authenticated user who can register or modify a TechDocs source. Unsafe Python YAML tags, markdown_extensions names and configuration, theme options, and extra_templates values can reach the documentation generator and cause unintended code execution. The resulting impact is limited to the files, credentials, network access, and other resources available to the TechDocs backend or build container. This issue is fixed in versions 1.14.6 and 1.15.4.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-88064 since 09/09/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit.

Upgrading to version 1.14.6 or 1.15.4 eliminates this vulnerability.

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Productinfo

Name

• Backstage

Version

• 1.14.0
• 1.14.1
• 1.14.2
• 1.14.3
• 1.14.4
• 1.14.5
• 1.15.0
• 1.15.1
• 1.15.2
• 1.15.3

Website

• Product: https://github.com/backstage/backstage/

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