CVE-2025-62398: Moodle MFA Bypass Vulnerability

CVE-2025-62398 Overview

CVE-2025-62398 is an authentication weakness in Moodle that permits attackers holding valid credentials to bypass multi-factor authentication (MFA) under specific conditions. The flaw is tracked under [CWE-287: Improper Authentication] and affects the Moodle learning management platform. Successful exploitation lets an authenticated user circumvent the second authentication factor, weakening the account protection model that MFA is designed to provide. Red Hat has published an advisory tracking downstream exposure of the issue.

Critical Impact

Attackers with stolen or legitimately obtained credentials can bypass MFA controls, undermining a primary defense against credential compromise and enabling account takeover of Moodle users.

Affected Products

• Moodle (see vendor advisory for specific affected versions)
• Red Hat distributions packaging vulnerable Moodle builds
• Deployments relying on Moodle's built-in MFA enforcement

Discovery Timeline

• 2025-10-23 - CVE-2025-62398 published to the National Vulnerability Database
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-62398

Vulnerability Analysis

The vulnerability resides in Moodle's authentication workflow, where the MFA enforcement path can be circumvented by an actor who already possesses valid primary credentials. Because the attacker must authenticate with a username and password first, exploitation requires prior credential compromise through phishing, credential stuffing, password reuse, or insider access. Once past the first factor, the flaw permits the session to proceed without satisfying the second factor under the affected conditions.

The attack is network-reachable and does not require user interaction. The impact is limited to partial confidentiality and integrity loss on the compromised account rather than full system takeover, but for Moodle deployments handling academic records, assessments, or personal data, account-level compromise is a meaningful exposure.

Root Cause

The root cause is classified as improper authentication [CWE-287]. Specific implementation details have not been disclosed by the vendor beyond the advisory description. The flaw allows the MFA verification step to be skipped or otherwise satisfied incorrectly when specific preconditions are met during the login flow.

Attack Vector

Exploitation requires network access to a vulnerable Moodle instance and valid low-privilege credentials for a target account. The attacker completes primary authentication and then exercises the flawed path in the MFA workflow to reach an authenticated session state without completing second-factor verification. No user interaction from the victim is required beyond the initial credential compromise.

No verified proof-of-concept code has been published. See the Red Hat CVE-2025-62398 Advisory and Red Hat Bug Report #2404431 for tracking details.

Detection Methods for CVE-2025-62398

Indicators of Compromise

• Successful Moodle login events for accounts enrolled in MFA that lack a corresponding second-factor challenge record
• Authentication events originating from unusual geolocations or ASNs for enrolled users
• Session establishment immediately following primary credential submission with no MFA log entry in between

Detection Strategies

• Correlate Moodle authentication logs to identify sessions that reach an authenticated state without a matching MFA verification event
• Alert on privileged account logins that skip expected MFA prompts, especially for teacher, manager, and site administrator roles
• Monitor for authentication anomalies such as impossible travel and new-device logins on MFA-enrolled accounts

Monitoring Recommendations

• Ship Moodle web server and application logs into a centralized SIEM for correlation with identity provider telemetry
• Enable verbose authentication logging in Moodle to capture the MFA state transitions during login
• Establish baseline login patterns for high-value accounts and alert on deviations

How to Mitigate CVE-2025-62398

Immediate Actions Required

• Upgrade Moodle to the fixed version identified in the vendor advisory as soon as a maintenance window permits
• Force a password reset for administrative and privileged accounts and reissue MFA enrollment where feasible
• Review recent authentication logs for evidence of MFA bypass patterns before applying the patch

Patch Information

Refer to the Red Hat CVE-2025-62398 Advisory and the Red Hat Bug Report #2404431 for fixed package versions and upstream Moodle release information. Apply the vendor-supplied update on all Moodle nodes and verify the version after deployment.

Workarounds

• Restrict Moodle administrative interfaces to trusted network ranges or VPN-only access until patched
• Enforce strong, unique passwords and rotate credentials for accounts with elevated privileges
• Where supported, layer an upstream identity provider (SSO with enforced MFA at the IdP) in front of Moodle so the second factor is validated outside the vulnerable code path

# Verify installed Moodle version after patching
php /path/to/moodle/admin/cli/cfg.php --name=release

# Restrict admin paths at the web server (nginx example)
location ~ ^/(admin|login)/ {
    allow 10.0.0.0/8;
    deny all;
}