CVE-2026-106456 Backstage: Inconsistent credential enforcement for overlapping proxy routes
Unauthenticated users can bypass credential checks on nested proxy routes if parent paths allow public access, exposing upstream services.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-106456?
CVE-2026-106456 is a medium-severity authentication bypass vulnerability in Linuxfoundation Backstage, published on 6 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-863
Which versions are affected by CVE-2026-106456?
2 open source packages ship an affected version, including @backstage/plugin-proxy-backend. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
@backstage/plugin-proxy-backend npm | From 0.5.0 | 0.6.18 |
@backstage/plugin-proxy-backend npm | From 0.5.0 | 0.6.18 |
Products include Linuxfoundation Backstage, Linuxfoundation Backstage\/Plugin-Proxy-Backend.
How do I fix CVE-2026-106456?
Upgrade @backstage/plugin-proxy-backend to 0.6.18 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-106456 being exploited?
There is no known exploitation of CVE-2026-106456 in the wild and no public exploit code.
Other vulnerabilities in Linuxfoundation Backstage
- CVE-2026-106501 Backstage: Sensitive information exposure in Scaffolder
- CVE-2026-106558 Backstage: Improper validation of TechDocs MkDocs configuration
- CVE-2026-88064 Backstage: Improper input validation in TechDocs MkDocs configuration
- CVE-2026-106459 Backstage: Improper input validation in Sentry scaffolder actions
- CVE-2026-106486 Backstage: Improper filesystem validation in Bitbucket pull-request scaffolder actions
Sources
Also known as GHSA-472h-9c5j-prrr.