CVE-2026-9084

CVE-2026-9084 is a medium-severity vulnerability with a CVSS 4.0 base score of 6.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Description

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.

Frequently asked questions

What is CVE-2026-9084?
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.
How severe is CVE-2026-9084?
CVE-2026-9084 has a CVSS 4.0 base score of 6.0, rated medium severity.
Is CVE-2026-9084 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-9084?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-9084 have an EU (EUVD) identifier?
Yes. CVE-2026-9084 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31123.
When was CVE-2026-9084 published?
CVE-2026-9084 was published on 2026-05-20 and last updated on 2026-06-17.

References

Other CWE-287 (Improper Authentication) vulnerabilities

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