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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | keycloak | < 26.2.16, < 26.4.12, < 26.6.2 | 26.2.16 |
| Red Hat | Red Hat build of Keycloak 26.2 | — | — |
| Red Hat | Red Hat build of Keycloak 26.2.16 | — | — |
| Red Hat | Red Hat build of Keycloak 26.4 | — | — |
| Red Hat | Red Hat build of Keycloak 26.4.12 | — | — |
| Red Hat | Red Hat Single Sign-On 7.6.13 | — | — |
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 7 | — | — |
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 8 | — | — |
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 9 | — | — |
| Red Hat | RHEL-8 based Middleware Containers | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Single Sign On 7 | rh-sso7-keycloak +1 | 18.0.20-1.redhat_00001.1.el7sso | RHSA-2026:76130, RHSA-2026:76129, RHSA-2026:76128 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | keycloak-26.5 +2 | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Maven | org.keycloak:keycloak-saml-core | < 26.6.2 | 26.6.2 | GHSA-p5mv-gj8j-xqgf |
Advisories 4
- WID-SEC-2026-1612 Keycloak: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 8, 2026
- RHSA-2026:76130 Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 9 Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:76129 Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 8 Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:76128 Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 7 Red Hat Security Advisories (RHSA) · Oct 20, 2026
References
- RHSA-2026:19594 vendor-advisory
- RHSA-2026:19595 vendor-advisory
- RHSA-2026:19596 vendor-advisory
- RHSA-2026:19597 vendor-advisory
- RHSA-2026:76128 vendor-advisory
- RHSA-2026:76129 vendor-advisory
- RHSA-2026:76130 vendor-advisory
- RHSA-2026:76132 vendor-advisory
- RHSA-2026:76134 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-7307 vdb-entry
- RHBZ#2476526 issue-tracking