redhat build-keycloak CVE-2026-18212 vulnerability in Red Hat Products
Published on September 16, 2026

Keycloak-services: keycloak-services: saml redirect deflate helpers leak native zlib state
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.

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Vulnerability Analysis

CVE-2026-18212 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Timeline

Reported to Red Hat.

Made public. 50 days later.

Weakness Type

What is a Memory Leak Vulnerability?

The software does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. This is often triggered by improper handling of malformed data or unexpectedly interrupted sessions. In some languages, developers are responsible for tracking memory allocation and releasing the memory. If there are no more pointers or references to the memory, then it can no longer be tracked and identified for release.

CVE-2026-18212 has been classified to as a Memory Leak vulnerability or weakness.


Products Associated with CVE-2026-18212

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Red Hat Build Keycloak
 
Red Hat Jboss Data Grid
 
Red Hat Jbosseapxp
 
Red Hat Single Sign On
 

Affected Versions

Red Hat build of Keycloak 26.4: Red Hat build of Keycloak 26.4: Red Hat build of Keycloak 26.4: Red Hat build of Keycloak 26.4.16: Red Hat build of Keycloak 26.4.16: Red Hat build of Keycloak 26.6: Red Hat build of Keycloak 26.6: Red Hat build of Keycloak 26.6: Red Hat build of Keycloak 26.6.7: Red Hat build of Keycloak 26.6.7: Red Hat build of Keycloak 26.6.7: Red Hat Data Grid 8: Red Hat JBoss Enterprise Application Platform Expansion Pack: Red Hat Single Sign-On 7: