pac4j-saml before 6.5.6 Session Destruction via Unsigned LogoutRequest

Advisories

pac4j-saml before 6.5.6 Session Destruction via Unsigned LogoutRequest

severity: medium
date: 8/29/2026
Affecting: pac4j >= 0, < 6.5.6
CVE: CVE-2026-82465
CWE: CWE-345 Insufficient Verification of Data Authenticity
CVSS: 6.9
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
References: Patch Commit
pac4j Security Advisory for pac4j-core, pac4j-oidc and pac4j-saml
https://github.com/pac4j/pac4j/blob/pac4j-parent-6.5.5/pac4j-saml/src/main/java/org/pac4j/saml/logout/impl/SAML2LogoutValidator.java
https://github.com/pac4j/pac4j
Credit: Joshua Rogers (AISLE Research)
Description: pac4j-saml before 6.5.6 does not require signature validation of SAML LogoutRequest messages in SAML2LogoutValidator.validateLogoutRequest(). When an IdP sends no SessionIndex, a session can be destroyed based solely on the NameID, allowing an unauthenticated attacker to submit an unsigned LogoutRequest with a guessed identifier (e.g., an email address used as NameID) to terminate a victim's SAML session.

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