CVE-1999-1106 in Kppp
Summary
by MITRE
Buffer overflow in kppp in KDE allows local users to gain root access via a long -c (account_name) command line argument.
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Analysis
by VulDB Data Team • 04/17/2026
The vulnerability described in CVE-1999-1106 represents a critical buffer overflow flaw within the kppp component of the KDE desktop environment, which was widely deployed in Unix-like operating systems during the late 1990s. This issue specifically affects the pppd (Point-to-Point Protocol daemon) utility that is integral to dial-up networking functionality. The vulnerability arises from insufficient input validation when processing command line arguments, particularly the -c flag that specifies account names for PPP connections. When a local user provides an excessively long account_name argument, the kppp utility fails to properly bounds-check the input, leading to memory corruption that can be exploited to execute arbitrary code with elevated privileges. This flaw falls under the Common Weakness Enumeration category CWE-121, which describes stack-based buffer overflow conditions, and more specifically aligns with CWE-787, indicating an out-of-bounds write vulnerability that occurs when a buffer is accessed beyond its allocated bounds.
The operational impact of this vulnerability is severe as it enables local privilege escalation from regular user level to root access, bypassing normal security controls that typically protect system resources. The exploitation process involves crafting a malicious command line argument that overflows the buffer allocated for account_name parameters, potentially overwriting adjacent memory locations including return addresses and control data. Attackers can leverage this vulnerability to execute arbitrary commands with the highest system privileges, effectively compromising the entire system. The attack vector is particularly concerning because it requires only local access to the system, making it accessible to any user who can execute the kppp utility. This aligns with the MITRE ATT&CK framework's privilege escalation techniques, specifically covering the T1068 (Local Privilege Escalation) and T1059 (Command and Scripting Interpreter) tactics that attackers might employ to establish persistent access or extract sensitive information from compromised systems.
The technical exploitation of this buffer overflow demonstrates how seemingly innocuous command line argument processing can become a critical security weakness when proper input validation is omitted. The kppp utility's failure to implement proper bounds checking on the account_name parameter creates a predictable memory corruption scenario that attackers can reliably exploit. The vulnerability's impact extends beyond immediate privilege escalation as it can serve as a foothold for more sophisticated attacks, including the installation of backdoors, data exfiltration, or further network reconnaissance activities. System administrators and security professionals should recognize that this vulnerability was particularly dangerous in multi-user environments where local access might be granted to untrusted users, and the lack of proper input sanitization in widely used desktop components like KDE utilities amplified the risk. Remediation efforts must include immediate patching of the affected KDE components, implementation of proper input validation measures, and consideration of privilege separation techniques to limit the potential damage from similar vulnerabilities in other system components. The vulnerability also highlights the importance of security testing for command line utilities and the need for comprehensive buffer overflow protection mechanisms in all software components that process external inputs.