CVE-2003-0792 in Fetchmail
Summary
by MITRE
Fetchmail 6.2.4 and earlier does not properly allocate memory for long lines, which allows remote attackers to cause a denial of service (crash) via a certain email.
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Analysis
by VulDB Data Team • 03/08/2021
The vulnerability identified as CVE-2003-0792 affects fetchmail versions 6.2.4 and earlier, representing a classic buffer overflow condition that manifests through improper memory allocation during email processing. This flaw specifically targets the handling of long lines within email messages, creating a scenario where maliciously crafted email content can trigger memory allocation failures that ultimately lead to application crashes and system unavailability. The vulnerability operates at the core of email retrieval functionality, where fetchmail acts as a mail retrieval client that downloads messages from remote mail servers for local delivery.
The technical implementation of this vulnerability stems from insufficient bounds checking and memory management within fetchmail's email parsing routines. When processing incoming email messages containing exceptionally long lines, the application fails to properly allocate sufficient memory buffer space to accommodate the data, resulting in memory corruption that causes the application to terminate unexpectedly. This type of memory allocation error falls under the CWE-122 category of "Heap-based Buffer Overflow" and represents a fundamental flaw in input validation and resource management practices. The vulnerability is particularly concerning because it can be exploited remotely through email transmission without requiring any authentication or privileged access to the target system.
The operational impact of CVE-2003-0792 extends beyond simple application instability to encompass broader service availability concerns and potential system compromise. When exploited successfully, this vulnerability can cause fetchmail processes to crash repeatedly, leading to denial of service conditions that prevent legitimate email retrieval operations from functioning properly. Organizations relying on fetchmail for email collection services would experience significant disruption to their email infrastructure, potentially affecting business continuity and communication workflows. The remote exploitability means that attackers can trigger the vulnerability simply by sending specially crafted email messages to targeted systems, making this a particularly dangerous flaw in environments where fetchmail is used to process emails from untrusted sources.
Mitigation strategies for this vulnerability primarily focus on immediate software updates and patches to address the underlying memory allocation flaws in fetchmail versions prior to 6.2.5. System administrators should prioritize upgrading to patched versions of fetchmail as the most effective remediation approach, as this directly resolves the buffer overflow conditions that enable the exploitation. Additional defensive measures include implementing email filtering and content inspection mechanisms that can identify and block potentially malicious email content before it reaches the fetchmail processing layer. Network-level protections such as email gateway filtering and spam detection systems can provide additional layers of defense by identifying suspicious email patterns that may contain the long line payloads designed to trigger the vulnerability. Organizations should also consider implementing monitoring and alerting systems to detect abnormal application behavior that might indicate exploitation attempts, aligning with the ATT&CK framework's mitigation recommendations for process injection and execution techniques that could leverage similar memory corruption vulnerabilities.