High severity · published Oct 7, 2026
CVE-2026-106558
Backstage: Improper validation of TechDocs MkDocs configuration
8.8
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BA
backstage · backstage
< 1.50.7; >= 1.51.0-next.0, < 1.54.9; >= 1.55.0-next.0, < 1.55.2 · source: vendor, NVD
PL
plugin-techdocs-node · @backstage
< 1.14.8; >= 1.15.0, < 1.15.6; >= 2.0.0, < 2.0.1 · source: vendor
BP
Backstage Plugin-techdocs-node · Linuxfoundation
before 1.14.8; 1.15.0 before 1.15.6; 2.0.0 before 2.0.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-106558
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-106558
x_refsource_CONFIRM
https://github.com/backstage/backstage/security/advisories/GHSA-qmw3-745m-w99g
x_refsource_MISC
https://github.com/backstage/backstage/commit/32723a0fe4e12ed80535fc65d5331765c55aa91b
x_refsource_MISC
https://github.com/backstage/backstage/commit/944edb51c8524d3664b18f2d57ba101b1c93b709
x_refsource_MISC
https://github.com/backstage/backstage/commit/f18e9abcc6051491862b15e4fc60e69f8d52310c
x_refsource_MISC
https://github.com/backstage/backstage/releases/tag/v1.50.7
x_refsource_MISC
https://github.com/backstage/backstage/releases/tag/v1.54.9
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