CVE-2026-18212 Keycloak-services: keycloak-services: saml redirect deflate helpers leak native zlib state
An unauthenticated attacker can cause denial of service in Keycloak by sending repeated malformed SAML requests that leak native zlib memory.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-18212?
CVE-2026-18212 is a high-severity denial of service vulnerability in Red Hat Data Grid 8, published on 16 Sep 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 the SAML Redirect Binding implementation of Keycloak, an open-source identity and access management solution. The issue occurs because the custom DEFLATE compression and decompression helpers fail to release native zlib memory after use. An unauthenticated attacker can exploit this by sending repeated malformed SAML requests, leading to native memory exhaustion and a denial of service.
Weakness: CWE-401
Which versions are affected by CVE-2026-18212?
How do I fix CVE-2026-18212?
No fix has been published for CVE-2026-18212 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-18212 being exploited?
There is no known exploitation of CVE-2026-18212 in the wild and no public exploit code.
Sources
Also known as GHSA-wgrv-cjmx-4vfw.