CVE-2002-0146 in Fetchmail
Summary
by MITRE
fetchmail email client before 5.9.10 does not properly limit the maximum number of messages available, which allows a remote IMAP server to overwrite memory via a message count that exceeds the boundaries of an array.
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Analysis
by VulDB Data Team • 06/17/2024
The vulnerability identified as CVE-2002-0146 affects the fetchmail email client version 5.9.10 and earlier, presenting a critical memory corruption issue that arises from improper handling of message count limits within IMAP protocol interactions. This flaw stems from the client's failure to adequately validate or constrain the maximum number of messages that can be processed from a remote IMAP server, creating a scenario where malicious servers can exploit this weakness through crafted message count values.
The technical implementation of this vulnerability resides in the client's array boundary handling mechanisms during IMAP message processing operations. When fetchmail receives a message count from an IMAP server that exceeds the allocated array boundaries, the application fails to perform proper bounds checking before attempting to access memory locations beyond the intended array limits. This results in memory overwrites that can corrupt adjacent memory segments, potentially leading to application crashes or more severe exploitation scenarios where arbitrary code execution becomes possible.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential security breaches and system compromise. An attacker controlling a malicious IMAP server can leverage this flaw to cause fetchmail to overwrite critical memory regions, which may result in denial of service conditions or provide a foothold for more sophisticated attacks. The vulnerability is particularly concerning because it operates at the protocol level during legitimate email retrieval operations, making it difficult to detect through standard network monitoring approaches.
This vulnerability aligns with CWE-129, which addresses improper validation of array index bounds, and demonstrates characteristics consistent with memory corruption vulnerabilities that fall under ATT&CK technique T1059.007 for command and scripting interpreter. The flaw represents a classic buffer overflow condition where the application fails to enforce proper input validation before processing potentially malicious data from network sources. The lack of proper boundary checks during array access operations creates a predictable attack surface that can be exploited by remote adversaries without requiring local system access.
Mitigation strategies for CVE-2002-0146 focus primarily on updating to fetchmail version 5.9.10 or later, which contains the necessary patches to address the improper message count handling. Organizations should also implement network segmentation and access controls to limit exposure to potentially malicious IMAP servers, while monitoring for unusual message count values or connection patterns that might indicate exploitation attempts. Additionally, network administrators should consider implementing intrusion detection systems capable of identifying anomalous IMAP protocol behavior that could signal exploitation of this vulnerability.