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Fencer Vulns
high 7.7

CVE-2026-106509 json

Backstage: Improper validation of MkDocs theme configuration in TechDocs

published 2026-10-06 33 d ago modified 2026-10-09 30 d ago also GHSA-8w7q-29mw-gf5c , EUVD-2026-94074

cvss
7.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

Backstage is an open framework for building developer portals. Prior to 1.14.6, the @backstage/plugin-techdocs-node package is affected by improper validation of mkdocs theme configuration in techdocs. When TechDocs is configured to build documentation locally or in a container, a user with write access to a registered repository can include configuration values in mkdocs.yml that cause arbitrary code execution during the documentation build process. This issue is fixed in versions 1.14.6 and 1.15.4.

Patch / fix

  • npm @backstage/plugin-techdocs-node 1.15.4
  • linuxfoundation backstage_plugin-techdocs-node 1.14.6, 1.15.4
  • linuxfoundation backstage 1.50.5, 1.54.6

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-106509 updated cvss 7.7

plugin-techdocs-node: Backstage plugin-techdocs-node: Arbitrary code execution via improper MkDocs configuration validation

  • Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9 Red Hat Self-service automation portal 2 ansible-automation-platform/automation-portal, ansible-automation-platform/bootc-automation-portal-rhel9
    under investigation

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
32 d ago

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/backstage/backstage/commit/02cd7cdbb18b687446277b5602adaee7f1d53cbb referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/backstage/backstage/commit/a900a9953c8f7ad3ba1906d1d257725a9996cc9d referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.7 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
GitHub 3.1 7.7 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L

Affected packages

ecosystem package affected fixed in
npm @backstage/plugin-techdocs-node
<1.15.4
1.15.4

Affected products

  • backstage backstage
  • @backstage plugin-techdocs-node

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code
  • CWE-1336 Improper Neutralization of Special Elements Used in a Template Engine

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.