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CVE-2026-107602

Keycloak-services: keycloak-services: unauthenticated cpu exhaustion via saml 1.1 keyinfo infinite loop

High7.5EPSS 0.73%
Published
Updated
Reserved
Assigned by
redhat

Description

A flaw was found in the SAML 1.1 XML parsing logic of Keycloak, an open-source identity and access management solution. The issue occurs when the parser encounters unexpected elements within a security token's key information section, causing the processing thread to enter an infinite loop. An unauthenticated remote attacker could exploit this by sending specially crafted requests, leading to 100% CPU usage and a total denial of service that requires a server restart to resolve.

Scores

CVSS scores of CVE-2026-107602, by who scored it
Scored byCVSSScoreVector
redhatCNA (assigner)3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVDNVD · Awaiting Analysis3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.73% · top 45% of all CVEs (7 Nov 2026)
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The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

Affected products

What to do

Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. --- CME Mitigation Guidance (2026-11-06) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure. The highest-value action is to ensure the StAX-based XML parser in keycloak-saml-core advances the cursor or rejects unhandled child elements when parsing ds:KeyInfo in SAML 1.1 tokens: upgrade to Red Hat build of Keycloak 26.4.17, 26.6.8 (or the fixed Rhbk/Keycloak Rhel/Keycloak Services builds), which advances the cursor or rejects unexpected child elements within ds:KeyInfo rather than repeatedly peeking without advancing the parser, closing crafted SAML 1.1 request containing unexpected ds:KeyInfo child elements. Until patched, this is a concern on Keycloak deployments exposing unauthenticated SAML endpoints, so Restrict network access to Keycloak SAML endpoints such as /realms/{realm}/protocol/saml to trusted clients. As a compensating measure, Configure systemd service watchdogs (WatchdogSec and Restart) to monitor responsiveness and automatically restart Keycloak when worker threads hang and Implement rate limiting and connection throttling on unauthenticated HTTP requests targeting Keycloak SAML endpoints to mitigate thread exhaustion. These controls limit blast radius and contain exploitation, but they do not fix the underlying infinite-loop XML parsing defect — apply the upstream patch to fully remediate. Highest-impact CME: CME-1204 Service Watchdog and Automatic Restart (systemd WatchdogSec/Restart) (medium)

References (6)

Sources

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Record last updated .