CVE-2016-9299 in Jenkins
Summary
by MITRE
The remoting module in Jenkins before 2.32 and LTS before 2.19.3 allows remote attackers to execute arbitrary code via a crafted serialized Java object, which triggers an LDAP query to a third-party server.
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Analysis
by VulDB Data Team • 05/13/2026
The vulnerability identified as CVE-2016-9299 represents a critical remote code execution flaw within Jenkins' remoting module that affected versions prior to 2.32 and LTS versions before 2.19.3. This vulnerability stems from insufficient validation of serialized Java objects during remote communication processes, creating an avenue for malicious actors to inject arbitrary code execution payloads. The flaw specifically exploits the deserialization mechanism used by Jenkins' remoting capabilities, which are essential for distributed build execution and remote agent communication within the continuous integration environment.
The technical implementation of this vulnerability leverages Java's serialization framework to craft malicious objects that, when processed by the vulnerable Jenkins instance, trigger unintended behavior. Attackers can construct specially crafted serialized objects that contain malicious payloads designed to execute code on the target system. The vulnerability becomes particularly dangerous when combined with LDAP query functionality, as the serialized objects can contain references to external LDAP servers that the Jenkins instance will attempt to contact during the deserialization process. This creates a chain of execution where the LDAP query itself becomes a vector for code execution, allowing attackers to leverage the target system's network connectivity to fetch and execute malicious code from remote servers.
The operational impact of CVE-2016-9299 extends beyond simple remote code execution to encompass full system compromise capabilities. An attacker with network access to a Jenkins server could gain complete control over the build environment, potentially accessing source code repositories, credentials, and build artifacts. The vulnerability affects not just individual Jenkins installations but entire CI/CD pipelines, as compromised Jenkins servers could be used to attack downstream systems. This risk is particularly severe in enterprise environments where Jenkins serves as a central hub for automated builds and deployments, potentially providing attackers with access to production systems and sensitive data.
This vulnerability aligns with CWE-502, which addresses the deserialization of untrusted data, and maps to several ATT&CK techniques including T1059 for command and scripting interpreter and T1071 for application layer protocol. The attack pattern follows the typical exploitation sequence where an attacker crafts malicious input that bypasses security controls through improper validation of serialized data. Organizations using Jenkins in production environments faced significant risk as this vulnerability could be exploited without authentication, making it particularly dangerous in environments where Jenkins was accessible over the network. The remediation approach required immediate patching of Jenkins installations to versions that properly validate serialized objects and implement safeguards against deserialization of untrusted data. Additional mitigations included network segmentation to limit access to Jenkins servers, implementation of firewall rules to restrict LDAP communication, and regular security audits of Jenkins configurations to ensure proper hardening against similar vulnerabilities.