CVE-2002-1175 in Fetchmail
Summary
by MITRE
The getmxrecord function in Fetchmail 6.0.0 and earlier does not properly check the boundary of a particular malformed DNS packet from a malicious DNS server, which allows remote attackers to cause a denial of service (crash) when Fetchmail attempts to read data beyond the expected boundary.
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Analysis
by VulDB Data Team • 09/07/2025
The vulnerability identified as CVE-2002-1175 represents a classic buffer overflow condition within the fetchmail application that affects versions 6.0.0 and earlier. This flaw resides in the getmxrecord function which is responsible for processing mail exchange records from DNS servers during the email retrieval process. The vulnerability stems from insufficient input validation when processing DNS responses, specifically when encountering malformed DNS packets that exceed expected data boundaries. This particular issue demonstrates how network-based applications can be susceptible to crafted malicious responses that exploit memory management weaknesses in client-side software.
The technical implementation of this vulnerability involves the improper handling of DNS packet structures where the getmxrecord function fails to validate the length of incoming DNS data before attempting to parse and process it. When a malicious DNS server responds with a malformed packet that contains data extending beyond the expected buffer limits, the fetchmail application attempts to read beyond allocated memory boundaries. This results in memory corruption that ultimately leads to application crash and denial of service conditions. The vulnerability operates at the network protocol level where DNS resolution is performed, making it particularly dangerous as it can be exploited without requiring authentication or local access to the target system.
From an operational perspective, this vulnerability creates significant risk for email servers and clients that rely on fetchmail for email retrieval operations. The remote exploitation capability means that attackers can trigger the denial of service condition from any location on the network, making it particularly attractive for attackers seeking to disrupt email services. The impact extends beyond simple service disruption as it can be used as a component in larger attack campaigns or as a reconnaissance tool to identify vulnerable systems. Organizations using affected versions of fetchmail face potential downtime for email services and may experience reduced availability of critical communication infrastructure.
The vulnerability maps directly to CWE-121, which describes heap-based buffer overflow conditions, and can be categorized under ATT&CK technique T1499.3 for network denial of service attacks. Organizations should immediately upgrade to fetchmail version 6.0.1 or later where this vulnerability has been addressed through proper boundary checking and input validation. System administrators should also implement network monitoring to detect suspicious DNS traffic patterns that may indicate exploitation attempts. Additional mitigations include configuring firewalls to restrict DNS traffic to trusted servers only and implementing DNS security measures such as DNSSEC to prevent spoofing attacks that could exploit this vulnerability. The fix typically involves adding proper length validation checks before memory operations and implementing robust error handling for malformed DNS responses to prevent the application from attempting to process data beyond allocated buffers.