Public vulnerability disclosure

CVE-2026-117691

Keycloak-services: keycloak-services: saml redirect binding signature bypass via percent-encoded parameter names

publishedCWE-347

A flaw was found in the SAML HTTP-Redirect binding implementation of Keycloak. The issue occurs because the server processes percent-encoded parameter names (like %53AMLResponse) while the signature verification logic only checks literal parameter names. An attacker can use this discrepancy to provide a crafted, unsigned SAML message that the server processes instead of a legitimately signed one, leading to full account takeover of federated users.

Technical severity9.1 criticalCVSS 3.1 · CNA: redhat
Published2026-11-05Source updated 2026-11-05
Collected2026-11-051 attributed source

Fixes and workarounds

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.

Source: CNA: redhat

Affected products and versions

Affected products, source version ranges and reporting authorities
ProductVersionsAuthority
Red Hat Build of Keycloak
Red Hat
keycloak-services
https://access.redhat.com/downloads/content/package-browser/
Range not reported
Other versions: affected
CNA: redhat
Red Hat Build of Keycloak
Red Hat
rhbk/keycloak-rhel9
https://access.redhat.com/downloads/content/package-browser/
Range not reported
Other versions: affected
CNA: redhat
Red Hat Single Sign-On 7
Red Hat
keycloak-services
https://access.redhat.com/downloads/content/package-browser/
Range not reported
Other versions: unaffected
CNA: redhat

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

CVSS assessments

CVSS scores, vectors and reporting authorities
Version / scoreVectorAuthority
3.1 / 9.1
critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NCNA: redhat

Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

References

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