CVE-2000-0680 in CVS Server
Summary
by MITRE
The CVS 1.10.8 server does not properly restrict users from creating arbitrary Checkin.prog or Update.prog programs, which allows remote CVS committers to modify or create Trojan horse programs with the Checkin.prog or Update.prog names, then performing a CVS commit action.
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Analysis
by VulDB Data Team • 10/13/2025
The vulnerability identified as CVE-2000-0680 represents a critical security flaw in the Concurrent Versions System (CVS) version 1.10.8 server implementation. This issue stems from inadequate input validation and access control mechanisms within the CVS commit process, specifically concerning the handling of program files that are executed during checkin and update operations. The vulnerability allows remote authenticated users to exploit a directory traversal and file creation weakness that bypasses normal security restrictions imposed by the version control system.
The technical flaw manifests in the CVS server's improper handling of the Checkin.prog and Update.prog files that are automatically executed during commit operations. When a user performs a commit action, the CVS server processes these files to execute pre-commit and post-commit hooks respectively. However, the vulnerability occurs because the server does not adequately validate the file names or paths specified by users during the commit process. An attacker can manipulate the commit operation to create or overwrite these special program files in the repository with malicious code, effectively creating Trojan horse programs that will execute with the privileges of the CVS server process. This behavior directly violates the principle of least privilege and enables arbitrary code execution within the context of the version control system.
The operational impact of this vulnerability is severe and multifaceted. Remote attackers with commit privileges can escalate their access to the underlying system by planting malicious code that executes during normal commit operations. This creates a persistent backdoor within the version control infrastructure that can be leveraged for further attacks, data exfiltration, or system compromise. The vulnerability affects the integrity and confidentiality of the entire version control system since any committed code that triggers execution of these programs will execute malicious payloads. Additionally, the compromised system becomes a potential launching point for attacks against other systems within the network perimeter, as the CVS server typically runs with elevated privileges to access and modify repository files.
This vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and CWE-74, which addresses injection flaws. The issue also maps to ATT&CK technique T1059.001 for command and script injection, and T1546.001 for modification of system binaries, as attackers can manipulate the execution environment through the program files. Organizations using vulnerable CVS versions face significant risk of supply chain compromise, as the malicious code could be introduced into source code repositories and subsequently distributed to development environments. The exploitation requires only basic commit privileges, making it particularly dangerous as it can be leveraged by insiders or attackers who have gained access to legitimate user accounts within the version control system.
The recommended mitigations for this vulnerability include immediate upgrade to CVS version 1.11.1 or later, which contains the necessary patches to address the improper file handling. Organizations should also implement strict access controls and privilege separation for CVS users, ensuring that only trusted administrators have commit privileges. Additionally, regular monitoring of repository contents for suspicious program files and implementing automated scanning tools to detect potentially malicious code in commit operations can help identify exploitation attempts. Network segmentation and firewall rules should be implemented to limit access to CVS servers, while also ensuring that the server runs with minimal required privileges to reduce potential impact from successful exploitation. System administrators should also establish regular audits of the repository structure to detect unauthorized modifications to critical program files.