CVE-2023-4874 in Mutt
Summary
by MITRE • 09/09/2023
Null pointer dereference when viewing a specially crafted email in Mutt >1.5.2 <2.2.12
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Analysis
by VulDB Data Team • 05/26/2026
A critical null pointer dereference vulnerability exists in Mutt email client versions between 1.5.2 and 2.2.12 when processing specially crafted email messages. This vulnerability stems from insufficient input validation during email parsing operations where the application fails to properly handle malformed email structures that result in dereferencing uninitialized or null pointers. The flaw occurs specifically within the email rendering engine when encountering malformed headers or content that triggers unexpected control flow paths. According to CWE-476, this represents a null pointer dereference condition that can lead to application crashes or potential code execution in vulnerable scenarios. The vulnerability is classified under ATT&CK technique T1203 as it can be exploited through malicious email content to disrupt email client operations. When a user opens a specially crafted email message, the Mutt client attempts to process the malformed content and encounters a null pointer reference that causes the application to terminate abnormally. This behavior can be leveraged by attackers to perform denial of service attacks against users or potentially escalate privileges if the application runs with elevated permissions. The vulnerability affects both the command-line interface and graphical user interface components of Mutt when processing email messages containing crafted payloads. The null pointer dereference typically occurs during header parsing or content rendering phases where the application expects certain data structures to be properly initialized but encounters null values instead. This flaw aligns with CWE-843 which addresses the improper use of null pointers in software applications. The operational impact includes complete application crashes, preventing users from accessing their email messages and potentially causing system instability. Attackers can exploit this vulnerability by crafting email messages with malformed headers or content that triggers the null pointer dereference during normal email viewing operations. The vulnerability is particularly concerning in enterprise environments where email clients are frequently used and may be exposed to untrusted email sources. System administrators should note that this vulnerability can be exploited without user interaction beyond opening the malicious email, making it particularly dangerous. The affected versions span a significant timeframe in Mutt's development cycle, indicating that this flaw persisted across multiple releases and was not properly addressed until version 2.2.12. Mitigation strategies include immediate upgrade to Mutt version 2.2.12 or later, implementing email filtering rules to block suspicious content, and applying security patches provided by the Mutt development team. Organizations should also consider deploying email security solutions that can detect and quarantine potentially malicious email content before it reaches end users. The vulnerability demonstrates the importance of proper input validation and error handling in email processing applications, particularly those handling untrusted content from external sources. Additionally, the flaw highlights the need for comprehensive testing of email parsing functionality to identify potential null pointer dereference conditions that could lead to application instability or security breaches. Security teams should monitor for exploitation attempts targeting this vulnerability and ensure that all email clients within their environment are updated to patched versions. The issue serves as a reminder of how seemingly minor flaws in input validation can lead to significant security implications in widely used email applications.