CVE-2000-0442 in Qpopper
Summary
by MITRE
Qpopper 2.53 and earlier allows local users to gain privileges via a formatting string in the From: header, which is processed by the euidl command.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/14/2025
The vulnerability identified as CVE-2000-0442 represents a critical privilege escalation flaw within Qpopper version 2.53 and earlier implementations. This issue specifically targets the email server software's handling of the From: header field during message processing, creating a pathway for local attackers to execute arbitrary code with elevated privileges. The vulnerability stems from improper input validation and insecure string formatting practices within the euidl command, which processes incoming email headers without adequate sanitization measures.
The technical exploitation of this vulnerability occurs through a carefully crafted formatting string placed within the From: header field of an email message. When the vulnerable Qpopper server processes this malformed header, the euidl command fails to properly handle the string formatting directives, leading to a buffer overflow condition that can be leveraged to overwrite critical memory locations. This memory corruption allows the local attacker to manipulate the program's execution flow and ultimately execute code with the privileges of the Qpopper service account, typically running with elevated system permissions. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which directly enables privilege escalation attacks.
The operational impact of CVE-2000-0442 extends beyond simple privilege escalation, as it provides attackers with potential access to sensitive system resources and data. Once local users successfully exploit this vulnerability, they can potentially gain root access to the system, allowing them to modify system files, install malicious software, or establish persistent backdoors. The attack vector is particularly concerning because it requires only local access to the system, making it easier to exploit compared to remote attacks that require network exposure. This vulnerability aligns with ATT&CK technique T1068 which covers privilege escalation through local exploits, and T1059 for command execution via compromised services.
Mitigation strategies for this vulnerability require immediate patching of Qpopper installations to versions that properly handle string formatting operations and validate email header inputs. System administrators should disable unnecessary services and implement proper access controls to limit local user privileges. Additionally, monitoring for unusual email processing patterns and implementing intrusion detection systems can help identify exploitation attempts. The vulnerability demonstrates the importance of proper input validation and secure coding practices, particularly when handling user-supplied data in server applications. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of such local privilege escalation vulnerabilities, as they can serve as initial access points for broader system compromise attempts.