CVE-1999-1158 in Solaris
Summary
by MITRE
Buffer overflow in (1) pluggable authentication module (PAM) on Solaris 2.5.1 and 2.5 and (2) unix_scheme in Solaris 2.4 and 2.3 allows local users to gain root privileges via programs that use these modules such as passwd, yppasswd, and nispasswd.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-1158 represents a critical buffer overflow flaw affecting the pluggable authentication module architecture in early Solaris operating systems. This issue specifically impacts Solaris versions 2.3 through 2.5.1, creating a pathway for local attackers to escalate privileges to root level access. The vulnerability manifests in two primary components: the PAM implementation in Solaris 2.5.1 and 2.5, and the unix_scheme component present in Solaris 2.4 and 2.3. Both implementations suffer from insufficient input validation and bounds checking mechanisms that allow malicious data to overwrite adjacent memory locations.
The technical flaw stems from inadequate buffer size management within the authentication modules where user-supplied input is processed without proper bounds verification. When programs such as passwd, yppasswd, and nispasswd invoke these vulnerable PAM modules, they pass user credentials through functions that do not properly validate the length of input data. This allows attackers to overflow the allocated buffer space and overwrite critical memory segments including return addresses, function pointers, or other control data structures. The vulnerability is particularly dangerous because it leverages legitimate system utilities that are commonly used by both users and system processes, making detection more challenging and exploitation more straightforward.
The operational impact of this vulnerability is severe and far-reaching within Solaris environments. Local users who can execute programs utilizing these authentication modules can potentially gain complete system control through privilege escalation attacks. The attack vector is relatively simple as it requires only local access to the system and knowledge of the vulnerable programs. Once successfully exploited, attackers can execute arbitrary code with root privileges, effectively compromising the entire system. This vulnerability directly violates the principle of least privilege and undermines the fundamental security model of the operating system, as it allows unauthorized elevation of privileges through legitimate system interfaces.
The exploitability of this vulnerability aligns with ATT&CK technique T1068 which focuses on local privilege escalation through application misconfiguration. From a CWE perspective, this represents a classic buffer overflow vulnerability classified as CWE-121, where insufficient bounds checking leads to memory corruption. The affected components demonstrate poor input validation practices that are commonly addressed through secure coding guidelines and defensive programming techniques. Organizations should implement immediate mitigations including patching affected systems to the latest Solaris releases, disabling unnecessary authentication modules, and monitoring for suspicious privilege escalation attempts. Additionally, system administrators should consider implementing mandatory access controls and privilege separation mechanisms to limit the potential impact of such vulnerabilities in environments where patching may not be immediately possible.