CVE-2026-9084 MEDIUM

CVE-2026-9084: MISP OIDC authentication bypass via automatic email-based account linking under insecure IdP configurations

Vendor Misp
Product misp
Weakness CWE-287 · Improper authentication
Published May 20, 2026
Last update May 20, 2026

CVSS base score

6.0/10
Attack vector Adjacent
Attack complexity High
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

MISP’s OIDC authentication plugin allowed automatic linking of an OIDC identity to an existing local user account based on the email claim when the local account had no stored sub value. Under insecure or untrusted IdP configurations where email ownership is not enforced, an attacker with a valid OIDC token could assert a victim’s email address and authenticate as that user, leading to account takeover.

Key dates

02Disclosure timeline

May 20, 2026 CVE published
May 20, 2026 Record updated