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Fencer Vulns
high 8.5

CVE-2026-106486 json

Backstage: Improper filesystem validation in Bitbucket pull-request scaffolder actions

published 2026-10-06 33 d ago modified 2026-10-23 16 d ago also GHSA-g8rx-f7m5-7794 , EUVD-2026-94003

cvss
8.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

Backstage is an open framework for building developer portals. Prior to 0.3.10 in @backstage/plugin-scaffolder-backend-module-bitbucket-cloud and 0.2.25 in @backstage/plugin-scaffolder-backend-module-bitbucket-server, the Bitbucket pull-request Scaffolder actions did not sufficiently validate filesystem paths. An authenticated user who can execute an eligible template and influence an allowed Bitbucket repository could affect paths outside the expected working area, potentially compromising backend confidentiality, integrity, or availability. This issue is fixed in @backstage/plugin-scaffolder-backend-module-bitbucket-cloud 0.3.10 and @backstage/plugin-scaffolder-backend-module-bitbucket-server 0.2.25.

Patch / fix

  • npm @backstage/plugin-scaffolder-backend-module-bitbucket-cloud 0.3.10
  • npm @backstage/plugin-scaffolder-backend-module-bitbucket-server 0.2.25
  • linuxfoundation backstage/plugin-scaffolder-backend-module-bitbucket-cloud 0.3.10
  • linuxfoundation backstage/plugin-scaffolder-backend-module-bitbucket-server 0.2.25
  • linuxfoundation backstage 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-2026-106486 updated cvss 8.5

plugin-scaffolder-backend-module-bitbucket-cloud: plugin-scaffolder-backend-module-bitbucket-server: Backstage: Unauthorized file manipulation via Bitbucket pull-request Scaffolder actions

  • Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9
    not affected: vulnerable code not present

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
total
Assessed
32 d ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD 3.1 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
GitHub 3.1 8.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
npm @backstage/plugin-scaffolder-backend-module-bitbucket-cloud
<0.3.10
0.3.10
npm @backstage/plugin-scaffolder-backend-module-bitbucket-server
<0.2.25
0.2.25

Affected products

  • backstage backstage
  • @backstage plugin-scaffolder-backend-module-bitbucket-cloud
  • @backstage plugin-scaffolder-backend-module-bitbucket-server

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-59 Improper Link Resolution Before File Access

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.