CVE-2026-18212
Keycloak-services: keycloak-services: saml redirect deflate helpers leak native zlib state
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-401 |
| Vendor | red hat |
| Product | red hat build of keycloak 26.4 |
| Published | Sep 16, 2026 |
| Last Updated | Sep 16, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4
All versions affected Red Hat / Red Hat build of Keycloak 26.4.16
All versions affected Red Hat / Red Hat build of Keycloak 26.4.16
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6
All versions affected Red Hat / Red Hat build of Keycloak 26.6.7
All versions affected Red Hat / Red Hat build of Keycloak 26.6.7
All versions affected Red Hat / Red Hat build of Keycloak 26.6.7
All versions affected Red Hat / Red Hat Data Grid 8
All versions affected Red Hat / Red Hat JBoss Enterprise Application Platform Expansion Pack
All versions affected Red Hat / Red Hat Single Sign-On 7
All versions affected References
access.redhat.com: https://access.redhat.com/errata/RHSA-2026:68276 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:68277 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:68278 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:68280 access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-18212 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2508307
Credits
Red Hat would like to thank Paul Bottinelli (Trail of Bits in collaboration with OpenAI) for reporting this issue.