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WP OAuth Server - Security Vulnerability (CVE-2026-82843)

CVE-2026-82843

The WP OAuth Server ( Login with WordPress ) WordPress plugin before 6.4.0 does not bind the OpenID Connect identity assertion it issues to the authorization grant being exchanged, returning instead the assertion belonging to whichever user authenticated most recently, which allows users with the Subscriber role and above to obtain a validly signed identity assertion for another user, including an administrator, and authenticate as them at any application that uses the site for single sign-on.

CVE-2026-82843

CRITICAL CVSS 9.0 Published 2026-09-23 Updated 2026-09-24
AI Risk High (84/100) Active Exploit: No strong signal Published Exploit: No public exploit references Priority: P2 Urgent
Severity Band CRITICAL
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Affected Components 1
Reference Links 1
AI Risk Engine High (84/100)
Exploitability High
Active Exploitation No strong signal
Published Exploit Status No public exploit references

Threat Timeline

  1. 2026-09-23 CVE published and first recorded in the threat feed.
  2. 2026-09-24 Record updated with latest vulnerability metadata.
  3. 2026-10-01 AI technical context refreshed for mitigation and impact guidance.
  4. Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated 43 days ago

AI enriched 43 days ago (2026-10-01 17:05 UTC)

Technical Summary

The WP OAuth Server ( Login with WordPress ) WordPress plugin before 6.4.0 does not bind the OpenID Connect identity assertion it issues to the authorization grant being exchanged, returning instead the assertion belonging to whichever user authenticated most recently, which allows users with the Subscriber role and above to obtain a validly signed identity assertion for another user, including an administrator, and authenticate as them at any application that uses the site for single sign-on.

Potential Impact

Severity is CRITICAL (CVSS 9.0). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as High based on severity and technical exposure profile.

Primary risk drivers: severity and technical exposure profile

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

AI risk score 84/100 (High, High) with priority P2 Urgent. Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

Affected Products

WP OAuth Server PLUGIN · wp-oauth-server Affected: < 6.4.0 Fixed in: 6.4.0

References

What to do about this

Patch immediately Serious, and reachable without meaningful privilege.

Fix it

Update WP OAuth Server to 6.4.0 or later.

That is the complete fix. Everything below is what protects you in the meantime.

No Hack Halt control meaningfully contains this one — updating is the remedy. We would rather say so than sell you something that will not help.

Start free

Not sure if you are affected?

Scan your site to see whether it runs WP OAuth Server, and at which version.

Free, no installation, no account. It reads what your site already publishes, then tells you which plugins carry known vulnerabilities and what to do about each one.

Scan my site free See what Hack Halt does

Am I affected by this vulnerability?

You are affected if your site runs WP OAuth Server. Versions below 6.4.0 are vulnerable; that release and later are not. An attacker needs any registered account, so open registration materially increases the risk.

How do I fix it?

Update WP OAuth Server to version 6.4.0 or later. That is the complete fix.