CVE-2016-6497 in LDAP API
Summary
by MITRE
main/java/org/apache/directory/groovyldap/LDAP.java in the Groovy LDAP API in Apache allows attackers to conduct LDAP entry poisoning attacks by leveraging setting returnObjFlag to true for all search methods.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2016-6497 resides within the Apache Directory Groovy LDAP API, specifically in the LDAP.java file where the returnObjFlag parameter can be manipulated to enable LDAP entry poisoning attacks. This flaw represents a critical security weakness that allows attackers to manipulate LDAP search operations and potentially inject malicious objects into the search results. The vulnerability stems from improper handling of the returnObjFlag parameter which, when set to true, enables the API to return Java serialized objects from LDAP entries, creating an avenue for remote code execution through deserialization attacks. The issue is categorized under CWE-502 as Deserialization of Untrusted Data, which directly aligns with the attack vector involving object deserialization in LDAP contexts.
The technical exploitation of this vulnerability occurs when an attacker crafts LDAP search queries that leverage the returnObjFlag parameter set to true, allowing the API to deserialize and return Java objects from LDAP entries. This creates a dangerous scenario where malicious LDAP entries can contain serialized Java objects that, when processed by the vulnerable API, execute arbitrary code on the target system. The attack typically involves creating specially crafted LDAP entries containing malicious serialized objects that get deserialized during the search operation, enabling attackers to achieve remote code execution. This vulnerability is particularly dangerous because it operates at the protocol level and can be exploited without requiring authentication, making it a significant threat to systems that use the Groovy LDAP API for directory services integration.
The operational impact of CVE-2016-6497 extends beyond simple remote code execution to encompass complete system compromise and potential lateral movement within network environments. Organizations using the affected Groovy LDAP API are at risk of unauthorized access, data exfiltration, and system infiltration, especially in environments where LDAP is used for authentication and authorization services. The vulnerability affects systems that rely on LDAP for directory services and could potentially allow attackers to escalate privileges, access sensitive data, or establish persistent backdoors within the network infrastructure. This attack vector is particularly concerning in enterprise environments where LDAP is commonly used for user authentication and access control, as it could enable attackers to gain elevated privileges and compromise the entire directory service infrastructure.
Mitigation strategies for CVE-2016-6497 primarily involve immediate patching of the affected Apache Directory Groovy LDAP API components and implementing strict controls over LDAP search operations. Organizations should disable or restrict the use of the returnObjFlag parameter in LDAP search methods, particularly when dealing with untrusted LDAP servers or entries. The recommended approach includes configuring applications to avoid setting returnObjFlag to true unless absolutely necessary and implementing proper input validation and sanitization for all LDAP queries. Additionally, network segmentation and monitoring should be enhanced to detect suspicious LDAP activities that might indicate exploitation attempts. Security teams should also consider implementing application whitelisting controls and restricting LDAP connectivity to only trusted sources, following the principle of least privilege as outlined in the MITRE ATT&CK framework for credential access and defense evasion techniques. The vulnerability demonstrates the importance of secure coding practices and proper object deserialization controls in network services, emphasizing the need for comprehensive security testing and code review processes to prevent similar issues in the future.