CVE-2026-18212: Red Hat Build Of Keycloak 26.4

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Red Hat Red Hat Build Of Keycloak 26.4: before 26.4.16-2 (fixed in 26.4.16-2); before 26.4-26 (fixed in 26.4-26)
• Red Hat Red Hat Build Of Keycloak 26.4.16
• Red Hat Red Hat Build Of Keycloak 26.6: before 26.6.7-3 (fixed in 26.6.7-3); before 26.6-20 (fixed in 26.6-20)
• Red Hat Red Hat Build Of Keycloak 26.6.7
• Red Hat Red Hat Data Grid 8
• Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack
• Red Hat Red Hat Single Sign-On 7

Published 2026-09-16. Last modified 2026-09-16.