Bug 2547937 (CVE-2026-107602)
| Summary: | CVE-2026-107602 keycloak-services: keycloak-services: Unauthenticated CPU exhaustion via SAML 1.1 KeyInfo infinite loop | ||
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| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security <prodsec-ir-bot> |
| Status: | NEW --- | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | unspecified | CC: | aschwart, aszczucz, boliveir, drichtar, mposolda, pjindal, rmartinc, security-response-team, ssilvert, sthorger, vmuzikar |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
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.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Deadline: | 2027-01-05 | ||
A flaw was found in Keycloak's SAML 1.1 XML parsing logic within the keycloak-saml-core component. When parsing the ds:KeyInfo element in SAML 1.1 assertions, the StAX-based parser loops over child elements but only contains logic to handle specific expected tags such as ds:EncryptedKey, ds:X509Data, and ds:KeyValue. The parser lacks a fallback branch to consume or reject other valid child elements like ds:KeyName. Consequently, the parser repeatedly peeks at the unhandled element without advancing, causing the processing thread to enter an infinite loop spinning at 100% CPU. An unauthenticated remote attacker can exploit this by sending crafted SAML requests to Keycloak's SAML endpoints (e.g., /realms/{realm}/protocol/saml). By sending multiple concurrent requests, an attacker can exhaust the worker thread pool, resulting in a permanent denial of service until the server is manually restarted.