CVE-2025-14840: Drupal HTTP Client Manager Auth Bypass

CVE-2025-14840 Overview

An Improper Check for Unusual or Exceptional Conditions vulnerability has been identified in the Drupal HTTP Client Manager module. This security flaw allows attackers to perform Forceful Browsing attacks, potentially bypassing access controls and reaching resources that should be restricted. The vulnerability stems from inadequate validation of unusual or exceptional conditions during HTTP client operations.

Critical Impact

This vulnerability enables network-based attackers to cause denial of service conditions without requiring authentication or user interaction, potentially disrupting availability of affected Drupal installations.

Affected Products

• Drupal HTTP Client Manager versions from 0.0.0 before 9.3.13
• Drupal HTTP Client Manager versions from 10.0.0 before 10.0.2
• Drupal HTTP Client Manager versions from 11.0.0 before 11.0.1

Discovery Timeline

• 2026-01-28 - CVE CVE-2025-14840 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2025-14840

Vulnerability Analysis

This vulnerability is classified under CWE-754 (Improper Check for Unusual or Exceptional Conditions). The HTTP Client Manager module fails to properly validate and handle unusual or exceptional conditions when processing HTTP client requests. This deficiency allows attackers to exploit the module through Forceful Browsing techniques.

The attack can be executed remotely over the network with low complexity, requiring no privileges or user interaction. While the vulnerability does not impact confidentiality or integrity, it poses a significant threat to system availability, potentially allowing attackers to exhaust resources or cause service disruptions.

Root Cause

The root cause lies in the HTTP Client Manager module's failure to implement proper exception handling and validation for unusual input conditions. When the module encounters unexpected states or malformed requests, it does not adequately check for and handle these exceptional conditions, creating an exploitable gap in the security posture.

Attack Vector

The attack vector is network-based, allowing remote exploitation. Attackers can leverage Forceful Browsing techniques to access resources or trigger conditions that the application fails to handle properly. The attack requires no authentication (privileges: none) and no user interaction, making it highly accessible to potential attackers.

The vulnerability can be exploited by sending specially crafted HTTP requests that trigger the improper condition checks, potentially leading to denial of service through resource exhaustion or application crashes.

Detection Methods for CVE-2025-14840

Indicators of Compromise

• Unusual HTTP request patterns targeting the HTTP Client Manager module endpoints
• Elevated error rates or exception logs in Drupal watchdog related to HTTP client operations
• Resource exhaustion symptoms such as increased memory usage or CPU spikes during HTTP client processing
• Application crashes or unresponsive behavior following HTTP client requests

Detection Strategies

• Monitor Drupal application logs for unusual exception messages related to the HTTP Client Manager module
• Implement web application firewall (WAF) rules to detect and block Forceful Browsing attack patterns
• Deploy network intrusion detection systems (IDS) to identify anomalous HTTP request sequences
• Review access logs for repeated requests to restricted resources or unexpected URL patterns

Monitoring Recommendations

• Enable verbose logging for the HTTP Client Manager module during investigation periods
• Set up alerts for abnormal traffic patterns targeting Drupal installations
• Monitor system resource utilization (CPU, memory) for signs of denial of service conditions
• Track error rates in application performance monitoring tools

How to Mitigate CVE-2025-14840

Immediate Actions Required

• Update Drupal HTTP Client Manager to version 9.3.13 or later for the 9.x branch
• Update Drupal HTTP Client Manager to version 10.0.2 or later for the 10.x branch
• Update Drupal HTTP Client Manager to version 11.0.1 or later for the 11.x branch
• Review Drupal watchdog logs for any signs of exploitation attempts
• Consider temporarily disabling the HTTP Client Manager module if patching is not immediately possible

Patch Information

Security patches are available through the official Drupal security advisory. Administrators should update to the following patched versions based on their current installation:

• Version 9.x: Upgrade to 9.3.13 or later
• Version 10.x: Upgrade to 10.0.2 or later
• Version 11.x: Upgrade to 11.0.1 or later

For detailed patch information and update instructions, refer to the Drupal Security Advisory SA-CONTRIB-2025-126.

Workarounds

• If immediate patching is not feasible, consider disabling the HTTP Client Manager module temporarily
• Implement rate limiting on HTTP requests to the Drupal installation
• Deploy a web application firewall (WAF) with rules to detect and block Forceful Browsing attacks
• Restrict network access to the Drupal administration interface to trusted IP addresses only

# Drupal Drush command to update the HTTP Client Manager module
drush pm:update http_client_manager

# Alternative: Using Composer to update the module
composer update drupal/http_client_manager

# Clear Drupal cache after updating
drush cache:rebuild