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Vulnerability · Published Oct 7, 2026 · Assigned by GitHub_M

CVE-2026-106558Backstage: Improper validation of TechDocs MkDocs configuration

High 8.8

In plain English

A high-severity unsafe deserialization in backstage from backstage. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.5%top 59.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npm@backstage/plugin-techdocs-node1.15.4GHSA-qmw3-745m-w99g

Affected products (as reported)

VendorProductVersions
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

Weakness: CWE-502 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References