CVE-2026-106456

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Backstage is an open framework for building developer portals.

Vendor / product: Linuxfoundation — backstage\/plugin-proxy-backend

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

6.5

6.5 (CVSS v3.1)

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

Severity source: NVD CVSS v3.1 (nvd@nist.gov)

Timeline (UTC)

Published: 2026-10-06 21:17

Modified: 2026-10-27 20:51

NVD status: Analyzed

Last synced 19 hours ago

Verified against the source API 2026-10-28 11:30 UTC

Exploitation

Not listed in CISA KEV (as of last catalog sync)

Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).

Affected products

linuxfoundation / backstage\/plugin-proxy-backend ≥0.5.0 <0.6.18

linuxfoundation / backstage ≥1.28.0 <1.55.0

Weakness classification (CWE)

CWE-863

Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.

Mitigation & advisories

Vendor advisory: https://github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrr

Patch / mitigation: https://github.com/backstage/backstage/commit/9df92923ac32558bb80edeceafd8de780c44e218

Patch / mitigation: https://github.com/backstage/backstage/releases/tag/v1.55.0

Patch / mitigation: https://github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrr

References

https://github.com/backstage/backstage/commit/9df92923ac32558bb80edeceafd8de780c44e218 security-advisories@github.com
https://github.com/backstage/backstage/releases/tag/v1.55.0 security-advisories@github.com
https://github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrr security-advisories@github.com

Data sources

NVD CVE API 2.0 — fetched 2026-10-28 11:30 UTC · record ↗

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CVE-2026-106456

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Weakness classification (CWE)

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References

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