CVE-2005-0546 in IMAPd
Summary
by MITRE
Multiple buffer overflows in Cyrus IMAPd before 2.2.11 may allow attackers to execute arbitrary code via (1) an off-by-one error in the imapd annotate extension, (2) an off-by-one error in "cached header handling," (3) a stack-based buffer overflow in fetchnews, or (4) a stack-based buffer overflow in imapd.
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Analysis
by VulDB Data Team • 07/04/2025
The CVE-2005-0546 vulnerability represents a critical security flaw in Cyrus IMAPd server software versions prior to 2.2.11, exposing multiple buffer overflow conditions that collectively create significant exploitation opportunities for malicious actors. These vulnerabilities specifically target the core IMAP server functionality that handles email message retrieval and management, making them particularly dangerous in enterprise and organizational email environments where Cyrus IMAPd is commonly deployed.
The technical implementation of these buffer overflows demonstrates several distinct attack vectors that exploit different components of the IMAP server architecture. The first vulnerability occurs in the imapd annotate extension through an off-by-one error that allows attackers to manipulate memory boundaries and potentially overwrite adjacent memory locations. The second flaw manifests in cached header handling where similar off-by-one conditions create opportunities for memory corruption. The remaining vulnerabilities involve stack-based buffer overflows in both fetchnews and imapd components, where insufficient input validation allows attackers to exceed buffer boundaries and overwrite stack memory regions including return addresses and function parameters. These vulnerabilities fall under CWE-121, stack-based buffer overflow, and CWE-122, heap-based buffer overflow, with the stack-based nature making them particularly susceptible to controlled code execution.
The operational impact of these vulnerabilities extends beyond simple denial of service scenarios, as they provide attackers with the capability to execute arbitrary code with the privileges of the IMAP server process. This privilege escalation potential allows adversaries to gain unauthorized access to email servers, potentially leading to complete system compromise, data exfiltration, and persistent backdoor establishment. The attack surface is particularly concerning because IMAP servers typically operate with elevated privileges and may have access to sensitive organizational email data. Attackers could leverage these vulnerabilities to establish persistent access, monitor email communications, or use the compromised server as a pivot point for attacking other network resources, making this vulnerability particularly dangerous in multi-domain or enterprise environments.
The exploitation of these buffer overflows aligns with several techniques documented in the MITRE ATT&CK framework, particularly in the privilege escalation and execution phases of the attack lifecycle. The vulnerabilities map to ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation. Organizations running affected versions of Cyrus IMAPd should immediately implement mitigation strategies including patching to version 2.2.11 or later, implementing network segmentation to limit exposure, and deploying intrusion detection systems to monitor for exploitation attempts. Additionally, input validation hardening and address space layout randomization should be considered as supplementary defensive measures. The vulnerability highlights the critical importance of maintaining up-to-date server software and implementing robust security monitoring practices to detect and respond to exploitation attempts in enterprise email infrastructure.