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Improper Signature VerificationWeakness · CWE-347

CVE-2025-9485

CRITICAL · 9.8 CVSS v3.1 Published 2025-10-04
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The OAuth Single Sign On – SSO (OAuth Client) plugin for WordPress is vulnerable to Improper Verification of Cryptographic Signature in versions up to, and including, 6.26.12. This is due to the plugin performing unsafe JWT token processing without verification or validation in the `get_resource_owner_from_id_token` function. This makes it possible for unauthenticated attackers to bypass authentication and gain access to any existing user account - including administrators in certain configurations - or to create arbitrary subscriber-level accounts.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The OAuth SSO WordPress plugin fails to verify or validate JWT cryptographic signatures in the get_resource_owner_from_id_token function, allowing unauthenticated attackers to forge tokens and bypass authentication to access existing user accounts (including admins in certain configurations) or create arbitrary subscriber accounts.

MitigationUpdate the OAuth Single Sign On – SSO plugin to version 6.26.13 or later which implements proper JWT signature verification. Audit user accounts for unauthorized access.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if the OAuth SSO plugin is installed
    Navigate to WordPress Admin > Plugins and look for 'OAuth Single Sign On - SSO' or check the /wp-content/plugins/ directory for folders containing 'oauth-sso' or similar OAuth-related plugin names
    Affected if The plugin is installed and active
  2. Determine the installed plugin version
    In WordPress Admin > Plugins, click on the plugin name to view details, or inspect the plugin's main PHP file header for 'Version:' tag, or check /wp-content/plugins/oauth-sso/readme.txt for the stable tag
    Affected if Version is lower than 6.26.13 (vulnerable) or version cannot be determined
  3. Verify if OAuth/OIDC authentication is configured and active
    Check WordPress Admin > Settings > OAuth SSO settings page, look for configured Identity Providers (IdPs), enabled OAuth/SSO login options, and note which user roles can authenticate via SSO
    Affected if OAuth/OIDC authentication is enabled and connected to an Identity Provider, making the vulnerable function get_resource_owner_from_id_token actively used during login attempts
  4. Audit user accounts for unauthorized creations
    In WordPress Admin > Users, review all accounts created around the time the vulnerability became public (or recently), especially accounts with Subscriber role or administrative roles you did not create. Check user registration date and email addresses.
    Affected if Unexpected user accounts exist, particularly Subscriber accounts or admin accounts you did not create
  5. Review authentication logs for suspicious activity
    Check WordPress debug.log, server access logs, and any SSO plugin logs for repeated login attempts with invalid or malformed tokens, successful logins from unknown IP addresses, or authentication failures to the get_resource_owner_from_id_token function
    Affected if Logs show authentication anomalies such as forged token usage, successful logins without proper IdP authentication, or multiple failed signature validation attempts

You are affected if the OAuth Single Sign On plugin is installed with a version lower than 6.26.13 and OAuth/OIDC authentication is enabled, regardless of whether you have confirmed unauthorized account access yet.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update the OAuth Single Sign On – SSO plugin to version 6.26.13 or later which implements proper JWT signature verification. Audit user accounts for unauthorized access.

Recommended fix Moderate confidence

Latest version greater than 6.26.12 (contact vendor for exact fixed release)

  1. 1. Log in to the WordPress admin dashboard
  2. 2. Navigate to Plugins > Installed Plugins
  3. 3. Locate the 'OAuth Single Sign On – SSO (OAuth Client)' plugin
  4. 4. If an update is available, click 'Update Now' to upgrade to the latest version
  5. 5. After updating, verify the new version number is greater than 6.26.12
  6. 6. Test the OAuth login functionality to ensure the plugin continues to work correctly

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,390
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-9485 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data