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Description

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.

PUBLISHED Reserved 2026-04-28 | Published 2026-05-19 | Updated 2026-05-20 | Assigner redhat




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

Improper Validation of Syntactic Correctness of Input

Product status

Default status
affected

26.2.16-1 (rpm) before *
unaffected

Default status
affected

26.2-21 (rpm) before *
unaffected

Default status
affected

26.2-21 (rpm) before *
unaffected

Default status
unaffected

Default status
affected

26.4.12-1 (rpm) before *
unaffected

Default status
affected

26.4-17 (rpm) before *
unaffected

Default status
affected

26.4-17 (rpm) before *
unaffected

Default status
unaffected

Timeline

2026-05-12:Reported to Red Hat.
2026-05-19:Made public.

Credits

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

References

access.redhat.com/errata/RHSA-2026:19594 (RHSA-2026:19594) vendor-advisory

access.redhat.com/errata/RHSA-2026:19595 (RHSA-2026:19595) vendor-advisory

access.redhat.com/errata/RHSA-2026:19596 (RHSA-2026:19596) vendor-advisory

access.redhat.com/errata/RHSA-2026:19597 (RHSA-2026:19597) vendor-advisory

access.redhat.com/security/cve/CVE-2026-7307 vdb-entry

bugzilla.redhat.com/show_bug.cgi?id=2476526 (RHBZ#2476526) issue-tracking

cve.org (CVE-2026-7307)

nvd.nist.gov (CVE-2026-7307)

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