CVE-2024-9687: WP 2FA with Telegram Auth Bypass Flaw

CVE-2024-9687 Overview

CVE-2024-9687 is an authentication bypass vulnerability affecting the WP 2FA with Telegram plugin for WordPress, developed by dueclic. The flaw exists in versions up to and including 3.0 and stems from insufficient validation of a user-controlled key in the validate_tg action handler. Authenticated attackers holding subscriber-level access or higher can exploit the weakness to authenticate as any other user on the site, including administrators. The vulnerability is tracked under CWE-639: Authorization Bypass Through User-Controlled Key.

Critical Impact
A low-privileged authenticated user can bypass two-factor authentication and log in as an administrator, resulting in full site compromise.

Affected Products

WP 2FA with Telegram (two-factor-login-telegram) plugin for WordPress
All versions up to and including 3.0
WordPress sites relying on the plugin for 2FA enforcement

Discovery Timeline

2024-10-15 - CVE-2024-9687 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-9687

Vulnerability Analysis

The WP 2FA with Telegram plugin implements a second authentication factor by sending a verification code through Telegram. The validate_tg AJAX action handles verification of the code and finalizes login for the specified user. The handler accepts a user identifier from the request without confirming that the identifier belongs to the currently authenticated session.

Because the handler treats the supplied identifier as authoritative, an attacker who is already authenticated as a low-privileged subscriber can submit the identifier of any other account. The plugin then completes the login flow against that target account. The result is a horizontal and vertical privilege escalation delivered through the plugin's own 2FA validation path.

Root Cause

The root cause is an Insecure Direct Object Reference (IDOR) pattern in the validate_tg action, documented in the plugin source at class-wp-factor-telegram-plugin.php line 244. The code trusts a user-controlled key that identifies which account to log in, without validating that the key matches the requester's session.

Attack Vector

An attacker first registers or logs in as a subscriber-level user, which is often possible on sites with open registration. The attacker then invokes the validate_tg action while supplying the target administrator's user identifier. The plugin completes login as the administrator, granting full backend access. Exploitation requires only network access to the site's admin-ajax.php endpoint and valid low-privileged credentials.

No verified proof-of-concept code is publicly available. See the Wordfence vulnerability report for additional technical context.

Detection Methods for CVE-2024-9687

Indicators of Compromise

POST requests to admin-ajax.php with action=validate_tg originating from subscriber-level sessions
Successful administrator logins immediately preceded by a validate_tg request from a non-administrator session
Unexpected changes to administrator accounts, plugin installations, or theme files following validate_tg traffic
WordPress audit log entries showing session establishment for privileged users without a corresponding password authentication event

Detection Strategies

Inspect web server access logs for validate_tg action calls and correlate the requester's session with the resulting authenticated user
Deploy WordPress activity logging plugins that capture user switching and login events for privileged accounts
Alert on any privilege escalation from subscriber to administrator roles within a short time window

Monitoring Recommendations

Forward WordPress application logs and web server logs to a centralized SIEM for correlation across sessions
Baseline normal admin-ajax.php action distribution and flag anomalous spikes in validate_tg calls
Monitor for creation of new administrator accounts, changes to wp_users and wp_usermeta, and installation of unknown plugins

How to Mitigate CVE-2024-9687

Immediate Actions Required

Update the WP 2FA with Telegram plugin to a version later than 3.0 as soon as a patched release is available from the vendor
If no patched version is available, deactivate and remove the plugin from all WordPress installations
Force a password reset and terminate active sessions for all administrator accounts on affected sites
Review installed plugins, themes, and administrator accounts for unauthorized additions or modifications

Patch Information

The vulnerability affects all versions of the plugin up to and including 3.0. Site administrators should consult the WordPress plugin repository and the Wordfence advisory for patch availability and upgrade guidance.

Workarounds

Disable open user registration to reduce the attacker pool required to reach subscriber-level access
Restrict access to admin-ajax.php through a web application firewall rule that blocks the validate_tg action from non-privileged sessions
Replace the plugin with an alternative two-factor authentication solution until a fix is released
Enforce IP allowlisting on /wp-admin/ and /wp-login.php for administrator accounts

bash

# Example WordPress CLI commands to disable the vulnerable plugin
wp plugin deactivate two-factor-login-telegram
wp plugin delete two-factor-login-telegram

# Force logout of all active sessions
wp user session destroy --all --all-users