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Keycloak CVE-2026-79651

| EUVDEUVD-2026-80830 HIGH
Uncontrolled Resource Consumption (CWE-400)
2026-09-16 redhat GHSA-8qv5-pjhw-3gx4
7.5
CVSS 3.1 · Vendor: redhat
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Severity by source

Vendor (redhat) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
7.5 HIGH

Unauthenticated network-reachable endpoint with trivial complexity and no interaction (AV:N/AC:L/PR:N/UI:N); unbounded cache causes memory-exhaustion crash, so availability-only (A:H, C:N/I:N).

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
Sep 16, 2026 - 16:42 vuln.today
CVE Published
Sep 16, 2026 - 14:55 cve.org
HIGH 7.5

DescriptionCVE.org

A flaw was found in the theme localization endpoints of the keycloak-services component, which is the core service responsible for authentication flows and theme management in Keycloak. The issue occurs because the system accepts arbitrary locale tags from unauthenticated requests and stores them in a permanent in-memory cache without limits. An attacker can exploit this by sending a large number of unique locale tags, eventually causing the server to run out of memory and crash.

AnalysisAI

Unauthenticated remote memory exhaustion in Keycloak's theme localization endpoints allows any network-reachable attacker to crash the server by flooding the keycloak-services component with unique locale tags, each of which is retained indefinitely in an unbounded in-memory cache. The flaw affects Red Hat Build of Keycloak and Red Hat Single Sign-On 7 deployments where those endpoints are exposed to untrusted networks, and requires no credentials or user interaction (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, 7.5, CWE-400). …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
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Delivery
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Exploit
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Execution
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Persist
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Impact
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Vulnerability AssessmentAI

Exploitation Exploitation requires network reachability to Keycloak's theme localization endpoints (part of the keycloak-services authentication component); no authentication, credentials, or user interaction are needed. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a genuine, well-formed unauthenticated remote denial-of-service. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Patch available per vendor advisory: Red Hat has published errata RHSA-2026:68276, RHSA-2026:68277, RHSA-2026:68278 and RHSA-2026:68280 for CVE-2026-79651, so upgrade Red Hat Build of Keycloak and Red Hat Single Sign-On 7 to the fixed build listed in the errata matching your release stream, verifying the exact version at https://access.redhat.com/security/cve/CVE-2026-79651 since no precise patched version number is given in the available data. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, verify whether Red Hat Build of Keycloak or Red Hat Single Sign-On 7 theme localization endpoints are reachable from untrusted networks and, if not required, block external access or restrict them to trusted IP ranges; enable rate limiting and monitor memory utilization on affected systems. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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CVE-2026-79651 vulnerability details – vuln.today

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