CVE-2026-0976 Org.keycloak/keycloak-quarkus-server: keycloak: proxy bypass due to improper handling of matrix parameters in url paths
Attackers can bypass reverse proxy path filtering by using matrix parameters, exposing sensitive administrative endpoints in Keycloak deployments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-0976?
CVE-2026-0976 is a low-severity vulnerability in Red Hat Build of Keycloak, published on 15 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A flaw was found in Keycloak. This improper input validation vulnerability occurs because Keycloak accepts RFC-compliant matrix parameters in URL path segments, while common reverse proxy configurations may ignore or mishandle them. A remote attacker can craft requests to mask path segments, potentially bypassing proxy-level path filtering. This could expose administrative or sensitive endpoints that operators believe are not externally reachable.
Weakness: CWE-20
Which versions are affected by CVE-2026-0976?
2 open source packages ship an affected version, including org.keycloak:keycloak-quarkus-server.
| Package | Affected | Fixed in |
|---|---|---|
org.keycloak:keycloak-quarkus-server Maven | All versions to 26.2.5 | None |
org.keycloak:keycloak-quarkus-server Maven | All versions to 26.2.5 | None |
How do I fix CVE-2026-0976?
Apply the vendor's patch.
Is CVE-2026-0976 being exploited?
There is no known exploitation of CVE-2026-0976 in the wild and no public exploit code.
Sources
Also known as GHSA-v897-pv23-r8cw, MINI-37w7-7hpc-rh2x.