Medium 4.8Published Oct 6, 2026

CVE-2026-106456Backstage: Inconsistent credential enforcement for overlapping proxy routes

Updated under an hour ago (2026-10-19 07:30 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

Backstage is an open framework for building developer portals. From 0.5.0 until 0.6.18, the @backstage/plugin-proxy-backend package is affected by inconsistent credential enforcement for overlapping proxy routes. An operator can configure overlapping proxy paths with different credential requirements. When a parent path permits unauthenticated access and a nested path requires credentials, the parent exemption can also cover requests handled by the nested proxy. An unauthenticated caller may therefore reach the nested upstream through Backstage, including with static upstream credentials configured for that proxy. This issue is fixed in version 0.6.18.

CVSS: 4.8 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness (CWE): CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Undergoing Analysis
Record last updated: Oct 7, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

backstage backstage backstage:backstage (from the name)	from 1.28.0, < 1.55.0	CNA record
@backstage plugin-proxy-backend backstage:plugin_proxy_backend (from the name)	from 0.5.0, < 0.6.18	CNA record

References

https://github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrrx-refsource-confirm
https://github.com/backstage/backstage/commit/9df92923ac32558bb80edeceafd8de780c44e218x-refsource-misc
https://github.com/backstage/backstage/releases/tag/v1.55.0x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.