CVE-1999-0139 in Solaris
Summary
by MITRE
Buffer overflow in Solaris x86 mkcookie allows local users to obtain root access.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/17/2026
The vulnerability described in CVE-1999-0139 represents a critical buffer overflow flaw within the Solaris x86 implementation of the mkcookie utility. This issue resides in the system's cookie generation mechanism that is typically used for authentication purposes within the X Window System. The flaw manifests when the mkcookie utility processes user input without proper bounds checking, allowing an attacker to overflow a fixed-size buffer and potentially overwrite adjacent memory locations. The vulnerability specifically affects the x86 architecture implementation of Solaris operating systems, making it particularly concerning for systems running this particular platform variant. This buffer overflow condition creates an opportunity for privilege escalation, as the utility appears to execute with elevated privileges during its operation, enabling local attackers to leverage the flaw for unauthorized system access.
The technical implementation of this vulnerability stems from improper input validation within the mkcookie utility's handling of command-line arguments or configuration data. When the utility processes user-supplied data, it fails to enforce length constraints on input buffers, allowing maliciously crafted input to exceed allocated memory boundaries. This overflow can overwrite the return address on the stack or other critical program variables, enabling an attacker to redirect program execution flow. The vulnerability operates under CWE-121, which categorizes buffer overflow conditions where insufficient bounds checking allows memory corruption. The flaw particularly aligns with the ATT&CK framework's privilege escalation techniques, specifically targeting local execution and system binary manipulation to achieve root access. The buffer overflow occurs in a context where the utility may have setuid privileges, amplifying the impact of the vulnerability.
The operational impact of this vulnerability extends beyond simple local privilege escalation, as it provides attackers with a direct path to root access on affected Solaris x86 systems. Local users who can execute the mkcookie utility or influence its input parameters can leverage this flaw to gain complete system control, potentially leading to data compromise, system infiltration, or further lateral movement within a network. The vulnerability's exploitation requires minimal prerequisites, as it only necessitates local access to the system and knowledge of the affected utility's behavior. This makes it particularly dangerous in environments where local user access is not strictly controlled or where users may have legitimate reasons to execute the utility. The impact is further exacerbated by the fact that Solaris systems were commonly deployed in enterprise environments where root access represents the highest level of system privileges, making this vulnerability a prime target for attackers seeking persistent system control.
Mitigation strategies for CVE-1999-0139 should focus on immediate patching of the affected Solaris x86 systems through official vendor updates or security patches. Organizations should also implement restrictive access controls to prevent unauthorized local execution of the mkcookie utility, particularly in environments where local user access is not strictly managed. Network segmentation and monitoring for suspicious execution patterns of the utility can provide additional defensive layers. The vulnerability's characteristics align with ATT&CK technique T1068, which describes the use of local system exploitation to gain elevated privileges. System administrators should also consider implementing runtime protections such as stack canaries or address space layout randomization to make exploitation more difficult. Regular security audits should verify that no unauthorized modifications exist to the mkcookie utility or related authentication components. The vulnerability serves as a reminder of the importance of input validation and proper bounds checking in system utilities, particularly those with elevated privileges, and highlights the need for comprehensive security testing of system binaries.