CVE-2026-9084

Account takeover via automatic email-based OIDC linking

Published May 20, 2026 · Updated May 20, 2026

Authentication bypass in MISP 2.5.0 through 2.5.37 allows remote attackers with valid OIDC tokens to take over local accounts. The Oidc::authenticate method falls back from the token's sub claim to an email lookup and links a matching account whose stored sub is null without requiring verified email ownership. Exploitation requires OIDC to be enabled and an insecure or untrusted identity provider that lets the token holder assert a victim's email address.

CVSS severity6.0
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in MISP 2.5.0 through 2.5.37 allows remote attackers with valid OIDC tokens to take over local accounts. The Oidc::authenticate method falls back from the token's sub claim to an email lookup and links a matching account whose stored sub is null without requiring verified email ownership. Exploitation requires OIDC to be enabled and an insecure or untrusted identity provider that lets the token holder assert a victim's email address.

The record

CVE
CVE-2026-9084
Published
May 20, 2026
Updated
May 20, 2026
Vendor
MISP Project
Product
MISP
Classifications
CWE-287, T1078
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 20, 2026CVE publishedPublication date reported by the CVE source.
  2. May 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.5.0 <=2.5.37

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

MISP Project · MISPversion=2.5.0 <=2.5.37

Published CVSS scores

6.0CIRCLCVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1078Valid Accounts

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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