CVE-2018-1999043 in Jenkins
Summary
by MITRE
A denial of service vulnerability exists in Jenkins 2.137 and earlier, 2.121.2 and earlier in BasicAuthenticationFilter.java, BasicHeaderApiTokenAuthenticator.java that allows attackers to create ephemeral in-memory user records by attempting to log in using invalid credentials.
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Analysis
by VulDB Data Team • 03/17/2020
This vulnerability resides in Jenkins continuous integration and delivery platform where attackers can exploit a denial of service condition through improper handling of authentication attempts. The flaw exists in the BasicAuthenticationFilter.java and BasicHeaderApiTokenAuthenticator.java components within Jenkins versions 2.137 and earlier, as well as 2.121.2 and earlier. The vulnerability stems from the system's failure to properly validate and manage authentication attempts, allowing malicious actors to repeatedly submit invalid login credentials.
The technical implementation of this vulnerability involves the creation of ephemeral in-memory user records during failed authentication attempts. When an attacker submits invalid credentials, the system generates temporary user objects in memory without proper cleanup or rate limiting mechanisms. This process consumes system resources progressively, leading to memory exhaustion and ultimately causing the Jenkins instance to become unresponsive or crash entirely. The flaw demonstrates characteristics of CWE-400 weakness category related to resource exhaustion and improper input validation.
The operational impact of this vulnerability is significant as it can render Jenkins servers completely unavailable to legitimate users and administrators. Attackers can systematically consume memory resources through repeated failed authentication attempts, effectively creating a denial of service condition that disrupts continuous integration workflows and automated build processes. This vulnerability particularly affects organizations relying on Jenkins for critical software development and deployment operations where service availability is paramount.
Mitigation strategies should include immediate patching to versions beyond the affected releases, implementing rate limiting on authentication attempts, and configuring proper resource monitoring for memory consumption. Organizations should also consider implementing authentication throttling mechanisms and network-level controls to limit the number of connection attempts from single IP addresses. The vulnerability aligns with ATT&CK technique T1499.004 related to network denial of service and demonstrates the importance of proper resource management in authentication systems. Additionally, implementing proper input validation and access control measures can prevent unauthorized users from exploiting this flaw through credential stuffing or brute force attacks.