What is CVE-2025-31691?

CVE-2025-31691 is a critical-severity vulnerability in Drupal Oauth2 Server, classified under Missing Authorization. CVSS score: 9.8/10. Published 2025-03-31.

How severe is CVE-2025-31691?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Drupal Oauth2 Server

CVE-2025-31691

Missing Authorization vulnerability in Drupal OAuth2 Server allows Forceful Browsing.This issue affects OAuth2 Server: from 0.0.0 before 2.1.0.

Vulnerability class: Broken Access Control

Published 2025-03-31 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (33.6th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Drupal Oauth2 Server — versions 0.0.0
Oauth2 Server Project

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

www.drupal.org/sa-contrib-2025-020 (Third Party Advisory)

Frequently asked questions

What is CVE-2025-31691?: CVE-2025-31691 is a critical-severity vulnerability in Drupal Oauth2 Server, classified under Missing Authorization. CVSS score: 9.8/10. Published 2025-03-31.
How severe is CVE-2025-31691?: Critical severity. CVSS v3 base score is 9.8 out of 10.