CVE-2024-56841: Mendix LDAP Authentication Bypass Flaw

CVE-2024-56841 Overview

A Lightweight Directory Access Protocol (LDAP) injection vulnerability affects the Mendix LDAP module in all versions before V1.1.2. The flaw allows an unauthenticated remote attacker to manipulate LDAP queries and bypass username verification. Siemens disclosed the issue in security advisory SSA-314390. The vulnerability is tracked under [CWE-90] (Improper Neutralization of Special Elements used in an LDAP Query).

Successful exploitation grants attackers the ability to bypass authentication without credentials. Network exposure of affected Mendix applications makes this issue reachable across untrusted networks.

Critical Impact
Unauthenticated remote attackers can bypass username verification through LDAP injection, compromising authentication confidentiality and integrity.

Affected Products

Mendix LDAP module — all versions prior to V1.1.2
Applications built on the Mendix platform that integrate the vulnerable LDAP module
Siemens-managed deployments referenced in advisory SSA-314390

Discovery Timeline

2025-01-14 - CVE-2024-56841 published to NVD
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2024-56841

Vulnerability Analysis

The Mendix LDAP module fails to properly neutralize special characters supplied in user input before incorporating them into LDAP search filters. Attackers can inject metacharacters such as *, (, ), and logical operators into the username field. The crafted input alters the structure of the LDAP query executed against the directory backend.

The resulting query returns matching directory entries regardless of whether the supplied credentials correspond to a legitimate account. The attacker bypasses the username verification step that the authentication flow relies on. No prior credentials are required, and the attack proceeds entirely over the network.

Root Cause

The root cause is missing input sanitization on LDAP query construction. The module concatenates untrusted input directly into LDAP filter strings without escaping reserved characters according to RFC 4515. This pattern matches the [CWE-90] weakness class.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker sends a crafted authentication request to the Mendix application endpoint that consumes the LDAP module. By submitting wildcard or boolean-operator payloads in the username parameter, the attacker forces the LDAP filter to evaluate as true for arbitrary or all directory entries. Username verification is bypassed, which can lead to account access depending on the surrounding authentication logic.

No public proof-of-concept exploit code has been published. Refer to the Siemens Security Advisory SSA-314390 for vendor technical details.

Detection Methods for CVE-2024-56841

Indicators of Compromise

Authentication requests containing LDAP metacharacters such as *)(uid=*, *)(&, or unbalanced parentheses in the username field
Repeated authentication attempts from a single source against Mendix login endpoints with anomalous payload structures
Successful authentication events with usernames that do not match any provisioned user account
LDAP server logs showing filter strings with injected wildcards or boolean operators

Detection Strategies

Inspect HTTP request bodies and query parameters reaching Mendix authentication endpoints for LDAP metacharacters
Correlate Mendix application logs with directory server query logs to identify malformed filters
Apply web application firewall signatures that flag LDAP injection patterns in POST parameters
Use the Singularity Platform with OCSF-normalized log ingestion to correlate authentication anomalies across application and directory tiers

Monitoring Recommendations

Forward Mendix runtime logs and LDAP/Active Directory query logs to a centralized SIEM
Alert on authentication successes immediately preceded by failed attempts containing special characters
Track new sessions originating from external IP addresses that authenticate to accounts with no prior login history
Baseline LDAP filter patterns from the application and alert on deviations

How to Mitigate CVE-2024-56841

Immediate Actions Required

Upgrade the Mendix LDAP module to version V1.1.2 or later on all affected applications
Restrict network access to Mendix authentication endpoints using firewall rules or reverse proxy controls
Audit recent authentication logs for evidence of LDAP injection attempts and unauthorized access
Rotate credentials and review session activity for accounts that may have been accessed via the bypass

Patch Information

Siemens released a fixed version of the Mendix LDAP module in V1.1.2. Operators must update the module dependency in affected Mendix applications and redeploy. Refer to Siemens Security Advisory SSA-314390 for the official patch reference and version mapping.

Workarounds

Place a web application firewall in front of the Mendix application to filter LDAP metacharacters from authentication parameters
Apply input validation at the reverse proxy layer to reject usernames containing *, (, ), \, or null bytes
Limit exposure of the authentication endpoint to trusted network segments until the module is updated
Enforce multi-factor authentication on accounts to reduce the impact of username verification bypass

bash

# Example WAF rule (ModSecurity) to block LDAP metacharacters in the username field
SecRule ARGS:username "@rx [\*\(\)\\\\x00]" \
    "id:1056841,phase:2,deny,status:400,\
    msg:'Potential LDAP injection in username (CVE-2024-56841)',\
    tag:'CWE-90'"