Memory Exhaustion Vulnerability in Keycloak's Authentication Component
CVE-2026-79651

7.5HIGH

Key Information:

Vendor

Red Hat
Status
Red Hat Build Of Keycloak 26.4
Red Hat Build Of Keycloak 26.4.16
Red Hat Build Of Keycloak 26.6
Red Hat Build Of Keycloak 26.6.7
Vendor
CVE Published:
16 September 2026

What is CVE-2026-79651?

A flaw exists in the theme localization endpoints of the Keycloak services component, which is essential for managing authentication flows and theme settings. This vulnerability arises due to the acceptance of arbitrary locale tags from unauthenticated sources, which are then stored in an unlimited in-memory cache. An attacker can exploit this by sending numerous unique locale tags, ultimately overwhelming the server's memory, leading to potential service disruptions.

Affected Version(s)

Red Hat build of Keycloak 26.4 26.4-26

Red Hat build of Keycloak 26.4 26.4-26

Red Hat build of Keycloak 26.4 26.4.16-2

References

https://access.redhat.com/errata/RHSA-2026:68276
vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:68277
vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:68278
vendor-advisoryx_refsource_REDHAT

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Red Hat would like to thank yd1ng for reporting this issue.
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