CVE-1999-0013 in SSH
Summary
by MITRE
Stolen credentials from SSH clients via ssh-agent program, allowing other local users to access remote accounts belonging to the ssh-agent user.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability identified as CVE-1999-0013 represents a critical security flaw in the ssh-agent program that enables local users to compromise remote account access through stolen credentials. This vulnerability specifically affects the Secure Shell (SSH) authentication framework and demonstrates a fundamental weakness in how authentication credentials are managed and protected within local system environments. The issue stems from insufficient access controls and privilege separation mechanisms within the ssh-agent implementation, creating an exploitable condition where unauthorized local users can intercept and utilize authentication tokens intended for legitimate SSH operations.
The technical flaw manifests through improper permission handling and credential exposure within the ssh-agent daemon process. When ssh-agent runs with elevated privileges or maintains credentials in accessible memory locations, local users who can execute processes on the same system can potentially access these credential stores through various techniques including process memory inspection, file system enumeration, or exploitation of shared resource vulnerabilities. This weakness directly violates the principle of least privilege and demonstrates inadequate sandboxing of authentication processes. The vulnerability aligns with CWE-276, which addresses improper permissions for critical resources, and reflects the broader category of credential exposure issues that have plagued authentication systems for decades.
The operational impact of CVE-1999-0013 extends far beyond simple privilege escalation, as it enables unauthorized access to remote systems that may contain sensitive data, administrative privileges, or critical infrastructure components. An attacker exploiting this vulnerability can gain access to any remote accounts that were previously authenticated through the compromised ssh-agent process, potentially leading to complete system compromise, data exfiltration, or lateral movement within network environments. The attack vector is particularly dangerous because it requires minimal privileges to execute, often allowing a regular user to escalate their access to administrative accounts that have been authenticated through SSH. This vulnerability has been classified under the MITRE ATT&CK framework as part of the credential access tactics, specifically targeting the use of legitimate credentials to maintain access to systems.
Mitigation strategies for this vulnerability require immediate implementation of proper access control mechanisms and privilege separation within SSH implementations. System administrators should ensure that ssh-agent processes run with minimal required privileges and that authentication sockets and credential files are properly protected through appropriate file permissions and access controls. The implementation of mandatory access controls, process isolation, and regular security auditing of SSH configurations can significantly reduce the attack surface. Additionally, organizations should consider implementing SSH key management solutions that separate authentication from credential storage, employ hardware security modules for key storage, and establish regular monitoring for unauthorized access attempts to authentication processes. The vulnerability also emphasizes the importance of system hardening practices and adherence to security baseline configurations that prevent local users from accessing sensitive system components.