CVE-2026-9084
MediumCVSS 6.0Exploitation Probability (EPSS)
Low risk8th percentile - higher than 8% of all known CVEs
Summary
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.
Risk Assessment
An attacker can take over a user account if the IdP does not verify email ownership, potentially leading to data theft or privilege escalation.
Recommendation
Update MISP to a version that includes a fix preventing automatic account linking without verification. Configure the IdP to enforce email ownership verification.
Original NVD description (English source)
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.