CVE-2025-3625: Moodle Auth Bypass Vulnerability

CVE-2025-3625 Overview

CVE-2025-3625 is an authorization bypass vulnerability in Moodle, the open-source learning management system used by universities and enterprises worldwide. The flaw stems from improper access controls tied to user-controlled keys, classified as [CWE-639]. An authenticated attacker with low privileges can access sensitive student information and disrupt account access for users who have completed two-factor authentication (2FA). The vulnerability requires network access and low complexity to exploit, with no user interaction needed.

Critical Impact
Authenticated attackers can read sensitive student data and lock legitimate users out of their accounts post-2FA, breaking confidentiality and availability guarantees for the platform.

Affected Products

Moodle (multiple versions — see vendor advisory for ranges)
Red Hat distributions packaging Moodle
Self-hosted Moodle deployments running unpatched releases

Discovery Timeline

2025-04-25 - CVE-2025-3625 published to the National Vulnerability Database
2025-06-24 - Last updated in NVD database

Technical Details for CVE-2025-3625

Vulnerability Analysis

The vulnerability is an Insecure Direct Object Reference (IDOR) in Moodle, tracked under [CWE-639] — Authorization Bypass Through User-Controlled Key. Moodle does not consistently validate that the authenticated session has rights to the object referenced in a request. An attacker who supplies a modified identifier can read records belonging to other users, including student profile and enrollment data.

The same authorization gap affects session and login state handling. After a victim completes 2FA, an attacker abusing the flaw can disrupt the victim's session state and prevent successful login. The result is both information disclosure and a denial-of-service condition against authenticated users.

Exploitation requires a valid low-privilege Moodle account, which is realistic in academic environments where self-registration or student accounts are common. The EPSS probability is 0.356%, indicating limited observed exploitation activity at this time.

Root Cause

Moodle endpoints accept user-supplied identifiers — such as user IDs, session references, or resource keys — without enforcing an ownership or role check against the authenticated principal. The application trusts the identifier presented in the request rather than deriving it from the server-side session.

Attack Vector

The attack is delivered over the network against the Moodle web interface. An authenticated attacker manipulates request parameters that reference other users' objects. The vulnerability requires no social engineering and no elevated privileges. The web request flow targets vulnerable endpoints that accept tampered identifiers and return data or alter state belonging to a different account.

No verified public proof-of-concept code is available. Refer to the Red Hat CVE-2025-3625 Advisory and the Red Hat Bug Report #2359690 for vendor technical details.

Detection Methods for CVE-2025-3625

Indicators of Compromise

Web access logs showing the same authenticated session iterating sequential or unrelated user IDs across Moodle endpoints
Repeated 2FA-completed users reporting login failures or session resets without administrator action
Unusual reads against /user/profile.php, /user/view.php, or similar endpoints with IDs not associated with the requesting session

Detection Strategies

Enable Moodle event logging and ingest mdl_logstore_standard_log records into a SIEM for correlation across users and endpoints
Alert on a single account accessing many distinct user records within a short window
Compare userid parameters in request logs against the authenticated session ID and flag mismatches

Monitoring Recommendations

Monitor failed-login spikes for users who recently completed 2FA, which can indicate exploitation of the availability impact
Track HTTP 200 responses to requests containing user identifiers that do not match the session owner
Forward Moodle and reverse-proxy logs to centralized analytics for retroactive hunting after patch deployment

How to Mitigate CVE-2025-3625

Immediate Actions Required

Upgrade Moodle to the fixed release identified in the vendor advisory as soon as feasible
Restrict self-registration and audit existing low-privilege accounts that could be used to authenticate against vulnerable endpoints
Reset sessions and rotate 2FA recovery codes for any users showing signs of unauthorized account state changes

Patch Information

Moodle has released updates that enforce server-side authorization checks on the affected endpoints. Consult the Red Hat CVE-2025-3625 Advisory and the Red Hat Bug Report #2359690 for fixed package versions and distribution-specific guidance. Apply the patch in staging before production rollout to validate plugin compatibility.

Workarounds

Place Moodle behind a web application firewall and block requests where user-identifier parameters do not match the authenticated session
Limit network access to the Moodle instance to trusted networks or via VPN until patching completes
Temporarily disable features that expose user-specific lookups to non-administrative roles where business requirements allow

bash

# Example: verify installed Moodle version on a Linux host
php /var/www/moodle/admin/cli/cfg.php --name=release

# Example: tail the Moodle log table for cross-user access patterns
mysql -e "SELECT userid, action, target, COUNT(*) c \
  FROM mdl_logstore_standard_log \
  WHERE timecreated > UNIX_TIMESTAMP(NOW() - INTERVAL 1 DAY) \
  GROUP BY userid, action, target HAVING c > 50;" moodle