EUVD-2026-30883
GHSA-p5mv-gj8j-xqgf
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from Vendor (redhat).
CVSS VectorVendor: redhat
Lifecycle Timeline
1Blast Radius
ecosystem impact- 38 maven packages depend on org.keycloak:keycloak-saml-core (9 direct, 29 indirect)
Ecosystem-wide dependent count for version 26.6.2.
DescriptionCVE.org
A flaw was found in Keycloak. A remote, unauthenticated attacker can send a specially crafted XML input to the Security Assertion Markup Language (SAML) endpoint. This malicious input can cause high CPU usage and worker thread starvation, leading to a Denial of Service (DoS) where the server becomes unavailable.
AnalysisAI
Denial of service in Red Hat build of Keycloak allows remote unauthenticated attackers to exhaust CPU and worker threads by submitting specially crafted XML payloads to the SAML endpoint. The flaw renders the identity provider unavailable, disrupting authentication for all downstream applications relying on it. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV.
Technical ContextAI
Keycloak is an open-source identity and access management solution maintained by Red Hat that implements federation protocols including SAML 2.0. The vulnerability resides in the SAML endpoint's XML input validation logic and maps to CWE-1286 (Improper Validation of Syntactic Correctness of Input), a class of bugs where malformed or pathologically structured input is accepted by a parser without enforcing structural constraints. When such input reaches the SAML processing pipeline, parsing becomes computationally expensive, monopolizing worker threads in the application server's request-handling pool until legitimate authentication requests can no longer be serviced. The affected component is identified in CPE data as cpe:2.3:a:red_hat:red_hat_build_of_keycloak across all listed versions.
RemediationAI
No vendor-released patch version is identified at time of analysis in the supplied data; monitor the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-7307 and Bugzilla entry https://bugzilla.redhat.com/show_bug.cgi?id=2476526 for the fixed build and apply it as soon as available. Until a patch is published, compensating controls include restricting network access to the SAML endpoints (typically /realms/{realm}/protocol/saml) to known identity provider peers and service providers via a reverse proxy or WAF ACL, which reduces exposure but breaks federation with unlisted partners; deploying rate limiting on SAML POST/Redirect bindings to cap requests per source IP, which can blunt single-source flooding but is bypassed by distributed sources; placing a WAF rule that rejects abnormally large or deeply nested XML bodies before they reach Keycloak, which mitigates the parsing cost but may false-positive on legitimate complex assertions; and disabling SAML realms entirely if the deployment uses only OIDC, which eliminates the attack surface at the cost of breaking any SAML-dependent integrations.
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Same technique Denial Of Service
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