CVE-2026-106455: Backstage: Improper validation of MkDocs plugin configuration in TechDocs
Impact
An authenticated attacker with control over a TechDocs source repository could cause a documentation build to retrieve and publish data from network locations reachable by the build environment. Exposure depends on deployment topology, build mode, and target endpoint protections. Modern cloud metadata services that require tokens or special headers are not directly accessible through the affected behavior.
Patches
Upgrade @backstage/plugin-techdocs-node to a patched version for the applicable release line:
- 1.14.x: upgrade to 1.14.7 or later in that line, available in Backstage v1.50.6. - 1.15.x: upgrade to 1.15.5 or later, available in Backstage v1.54.8. - Current mainline: upgrade to 2.0.0 or later, available in Backstage v1.55.0.
The update removes MkDocs plugins outside the built-in allowlist. To retain additional plugins, review them and configure techdocs.generator.mkdocs.dangerouslyAllowAdditionalPlugins, or supply dangerouslyAllowAdditionalPlugins when creating the generator directly. Plugins supplied through defaultPlugins remain permitted.
Workarounds
- Restrict control of TechDocs source repositories and catalog registration to trusted maintainers. - Run documentation builders with outbound access to private and link-local networks denied. - Require token- or header-protected cloud instance metadata services.
Other sources
Backstage is an open framework for building developer portals. From 0.11.12 until 1.14.7 and 1.15.5, the @backstage/plugin-techdocs-node package is affected by improper validation of mkdocs plugin configuration in techdocs. An authenticated attacker with control over a TechDocs source repository could cause a documentation build to retrieve and publish data from network locations reachable by the build environment. Exposure depends on deployment topology, build mode, and target endpoint protections. Modern cloud metadata services that require tokens or special headers are not directly accessible through the affected behavior. This issue is fixed in @backstage/plugin-techdocs-node versions 1.14.7 and 1.15.5.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/@backstage/plugin-techdocs-nodeto a version that resolves this vulnerability.Fixed in 1.15.5 - Upgrade
Upgrade
npm/@backstage/plugin-techdocs-nodeto a version that resolves this vulnerability.Fixed in 1.14.7 - Upgrade
Upgrade
@backstage/plugin-techdocs-nodeto a version that resolves this vulnerability.Fixed in 2.0.0 - Upgrade
Upgrade
@backstage/plugin-techdocs-nodeto a version that resolves this vulnerability.Fixed in 1.14.7 - Upgrade
Upgrade
@backstage/plugin-techdocs-nodeto a version that resolves this vulnerability.Fixed in 1.15.5 - Configuration
If additional MkDocs plugins must be retained, review them and configure dangerouslyAllowAdditionalPlugins; the option can also be supplied when creating the generator directly.
@backstage/plugin-techdocs-node TechDocs MkDocs generator techdocs.generator.mkdocs.dangerouslyAllowAdditionalPlugins - Compensating control
Require token- or header-protected cloud instance metadata services.
- Compensating control
Restrict control of TechDocs source repositories and catalog registration to trusted maintainers.
- Compensating control
Run documentation builders with outbound access to private and link-local networks denied.
Event History
Frequently Asked Questions
Who can exploit this issue?
An attacker must be authenticated and able to control a TechDocs source repository. The impact also depends on whether the TechDocs build environment can reach the attacker-selected network location.
Are cloud instance metadata services exposed?
Modern cloud metadata services that require tokens or special headers are not directly accessible through this behavior. Other network locations reachable from the documentation build environment may still be retrievable and published.
Which deployments are most exposed?
Exposure depends on deployment topology, TechDocs build mode, and protections at the target endpoint. Environments where documentation builds have broad access to internal network services have greater potential exposure.
What versions contain the fix?
The issue is fixed in @backstage/plugin-techdocs-node versions 1.14.7 and 1.15.5.