Backstage: Improper input validation in proxy-backend

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-106491
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 21:17:18 UTC
Updated2026-10-06 21:17:18 UTC
DescriptionBackstage is an open framework for building developer portals. Prior to 0.6.17, the @backstage/plugin-proxy-backend package is affected by improper input validation in proxy-backend. An authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default. This issue is fixed in version 0.6.17.

Risk And Classification

Primary CVSS: v3.1 6.4 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Problem Types: CWE-20 | CWE-22 | CWE-20 CWE-20: Improper Input Validation | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
3.1CNADECLARED6.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Backstage Backstage affected < 1.54.6 Not specified
CNA @backstage Plugin-proxy-backend affected < 0.6.17 Not specified

References

ReferenceSourceLinkTags
github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a... [email protected] github.com
github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5 [email protected] github.com
github.com/backstage/backstage/releases/tag/v1.54.6 [email protected] github.com
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