Security fix · CVE-2026-115923
Backstage catalog rules can be bypassed for URL locations using encoded path segments
Published Oct 28, 2026 · catalog updated Oct 28, 2026 · Backstage catalog rules can
Last checked Nov 7, 2026. A connected source was read within the last 7 days.
Check if you run it
No confirmed exploitation is on record for CVE-2026-115923. EPSS is 0.32%. Act only if a listed version of Backstage catalog rules can is installed.
Gaps on this record
- The stored product name is a package slug. The name on this page is taken from the title (Backstage catalog rules can).
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- Medium6.5
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 0.32%
- Remediation
- Version ranges on file
- Affected products
- npm @backstage · npm @backstage/plugin-catalog-backend
## Summary matches URL-type locations against location patterns using the raw URL string submitted by the user, while URL readers resolve that same string in canonical form when fetching the location's content. A URL can therefore be crafted so that it appears to belong to a trusted location scope during rule evaluation, but is fetched from a different scope. ## Details When a deployment restricts catalog kinds to trusted URL prefixes using location patterns, applies glob matching directly to the raw string. The URL readers used for ingestion resolve the same target in canonical form, including normalizing percent-encoded dot segments. A registered location such as matches a pattern as a raw string, but resolves to and is fetched from when its content is read. An authenticated user with permission to register catalog locations ( ) can use this to have an entity from an untrusted source admitted as if it originated from a trusted location scope. ## Impact The crossed boundary is the operator-configured catalog ingestion policy: entity content from outside the trusted location scope is ingested as if it were within it. Downstream consequences depend on deployment configuration, for example actions taken with integration credentials by processors or scaffolder when acting on the ingested entity. The assessment of this report found no basis for impact claims beyond the ingestion policy boundary itself. ## Patches This is fixed in 3.9.2 (Backstage release 1.54.10) and 4.0.2 (Backstage release 1.56.1). Version 4.0.1 as published is not fixed. ## Workarounds No complete workaround is available for deployments that rely on URL location patterns to restrict catalog kinds. Restricting location registration permissions reduces exposure.
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- npm @backstageversion unspecified
- npm @backstage/plugin-catalog-backend0 → 3.9.2
- npm @backstage/plugin-catalog-backend4.0.0 → 4.0.2
- npm @backstage/plugin-catalog-backend< 3.9.2
- npm @backstage/plugin-catalog-backend<3.9.2||>=4.0.0 <4.0.2
- npm @backstage/plugin-catalog-backend>= 4.0.0, < 4.0.2
How to fix CVE-2026-115923
Upgrade
CVE-2026-115923 lists a fix boundary at 3.9.2. Compare the installed build with that boundary before you change production.
Version check
Affected < 3.9.2
Advisory
Open the cve_org record and follow its fix.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
No confirmed exploitation is on record for CVE-2026-115923. EPSS is 0.32%. Act only if a listed version of Backstage catalog rules can is installed.
Which versions are affected?
Compare what you have installed with 0 → 3.9.2, 4.0.0 → 4.0.2, < 3.9.2, <3.9.2||>=4.0.0 <4.0.2, >= 4.0.0, < 4.0.2. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
CWE-22: Path Traversal. EPSS 0.32%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Oct 28, 2026 · GitHub Advisory Database
Detected
## Summary matches URL-type locations against location patterns using the raw URL string submitted by the user, while URL readers resolve that same string in canonical form when fetching the location's content. A URL can therefore be crafted so that it appears to belong to a trusted location scope during rule evaluation, but is fetched from a different scope. ## Details When a deployment restricts
Oct 28, 2026 · GitHub Advisory Database
Fix available
@backstage/plugin-catalog-backend fixed in 3.9.2; @backstage/plugin-catalog-backend fixed in 4.0.2
Oct 28, 2026 · GitHub Advisory Database
Fix available
@backstage/plugin-catalog-backend fixed in 3.9.2
Oct 28, 2026 · GitHub Advisory Database
Fix available
@backstage/plugin-catalog-backend fixed in 4.0.2
Oct 28, 2026 · GitHub Advisory Database
Updated
## Summary matches URL-type locations against location patterns using the raw URL string submitted by the user, while URL readers resolve that same string in canonical form when fetching the location's content. A URL can therefore be crafted so that it appears to belong to a trusted location scope during rule evaluation, but is fetched from a different scope. ## Details When a deployment restricts
Sources
- CVE.orgVulnerability recordCVE-2026-115923
Official CVE identifier
cve.org - GitHub Advisory DatabasePackage advisoryGHSA-w658-mh9p-ww8f
Backstage catalog rules can be bypassed for URL locations using encoded path segments
github.com - GitLab Advisory DatabasePackage advisoryCVE-2026-115923
@backstage/plugin-catalog-backend matches URL-type locations against catalog.rules location patterns using the raw URL string submitted by the user, while URL readers resolve that same string in canonical form when fetching the location's content. A URL can therefore be crafted so that it appears to belong to a trusted location scope during rule evaluation, but is fetched from a different scope.
advisories.gitlab.com - GitLab Advisory DatabasePackage advisorynpm/@backstage/plugin-catalog-backend/CVE-2026-115923.yml
matches URL-type locations against + location patterns using the raw URL string submitted by the user, + while URL readers resolve that same string in canonical form when fetching the location's + content. A URL can therefore be crafted so that it appears to belong to a trusted + location scope during rule evaluation, but is fetched from a different scope." +date: "2026-10-28" +pubdate: "2026-10-2
gitlab.com - OpenSSF OSV / OSV ScannerPackage advisoryGHSA-w658-mh9p-ww8f
Backstage catalog rules can be bypassed for URL locations using encoded path segments
osv.dev
References
Freshness
Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.
- GitLab Advisory DatabaseOct 30, 2026
- GitHub Advisory DatabaseOct 30, 2026
- CVE.orgOct 29, 2026
- GitLab Advisory DatabaseOct 29, 2026
- OpenSSF OSV / OSV ScannerOct 29, 2026