CVE-2026-106456

4.8 MEDIUM 0.2% exploit odds Fix listed Auth & access Web app

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. Limited direct impact.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-10-06 21:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-27 20:51 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 4.8 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-10-06 21:17 UTC
Last modified: 2026-10-27 20:51 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-863 · Incorrect authorization
Record status: Analyzed

Affected

Linuxfoundation backstage\/plugin-proxy-backend < 0.6.18
Linuxfoundation Backstage < 1.55.0

Attack profile CVSS 3.1 · 4.8

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-106456.md and follow it. Check whether this project is affected by CVE-2026-106456. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record