dbcve.org
Oauth2 ServerDrupal extension · Oauth2 Server Project

CVE-2025-31691

CRITICAL · 9.8 CVSS v3.1 Published 2025-03-31
Fix available
A fix is available. Upgrade to 2.1.0 or later.
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
Missing Authorization vulnerability in Drupal OAuth2 Server allows Forceful Browsing.This issue affects OAuth2 Server: from 0.0.0 before 2.1.0.

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 Drupal OAuth2 Server module versions before 2.1.0 contain a missing authorization vulnerability that allows forceful browsing. An unauthenticated or unauthorized attacker can directly access protected OAuth2 endpoints or resources by manipulating request URLs, bypassing intended access controls.

MitigationUpgrade Drupal OAuth2 Server to version 2.1.0 or later to obtain the authorization fixes. If immediate upgrade is not possible, restrict access to OAuth2 endpoints at the web server or firewall level until the patch can be applied.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Oauth2 ServerDrupal extension
Affected:< 2.1.0

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 OAuth2 Server module is installed
    Locate the oauth2_server module directory in your Drupal installation (typically under modules/contrib/oauth2_server or modules/oauth2_server) or check via Drupal admin interface at /admin/modules
    Affected if The module directory or listing shows oauth2_server is present in the Drupal installation
  2. Determine installed OAuth2 Server version
    Open the oauth2_server.info.yml or composer.json file in the module directory and read the version field, or run 'drush pm-list --filter=oauth2_server' to list the module version
    Affected if The reported version number is lower than 2.1.0 (for example 2.0.x, 1.x, or any version < 2.1.0)
  3. Verify OAuth2 endpoints are configured
    Check your Drupal site configuration for OAuth2 client registrations or authorization server settings - look for paths under /admin/config/people/oauth2-server or inspect the oauth2_server configuration in the config management system
    Affected if OAuth2 endpoints are defined and active (the vulnerability only affects environments with configured OAuth2 endpoints)
  4. Confirm endpoint accessibility
    Test accessing protected OAuth2 endpoints (such as /oauth/authorize, /oauth/token, or custom resource endpoints) using a request without valid authentication tokens to verify if authorization is bypassed
    Affected if Protected OAuth2 endpoints return successful responses without requiring valid authorization credentials

You are affected if the OAuth2 Server module is installed with any version prior to 2.1.0 AND OAuth2 endpoints are configured on your Drupal site.

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
Upgrade available Upgrade to 2.1.0 or later
Fixed in 2.1.0
Interim mitigation

Upgrade Drupal OAuth2 Server to version 2.1.0 or later to obtain the authorization fixes. If immediate upgrade is not possible, restrict access to OAuth2 endpoints at the web server or firewall level until the patch can be applied.

Recommended fix High confidence

2.1.0

  1. Update the Drupal OAuth2 Server module to version 2.1.0 or later
  2. Run database updates if any are required: drush updatedb or via the web UI at /update.php
  3. Clear Drupal caches: drush cr or via the admin UI
  4. Verify the OAuth2 Server module is reporting version 2.1.0 or higher at admin/modules
  5. Test OAuth2 authentication flows to confirm the fix does not break existing functionality
Caveat Review release notes for any configuration or behavioral changes between your current version and 2.1.0 before upgrading in production

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

Fix this in Oauth2 Server Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,656.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-31691 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2025-31691 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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