CVE-2006-5298 in mail client
Summary
by MITRE
The mutt_adv_mktemp function in the Mutt mail client 1.5.12 and earlier does not properly verify that temporary files have been created with restricted permissions, which might allow local users to create files with weak permissions via a race condition between the mktemp and safe_fopen function calls.
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Analysis
by VulDB Data Team • 04/24/2026
The vulnerability described in CVE-2006-5298 represents a critical race condition flaw within the Mutt mail client version 1.5.12 and earlier, specifically within the mutt_adv_mktemp function. This issue stems from improper verification of temporary file permissions during the file creation process, creating a window of opportunity for local attackers to exploit the system. The flaw occurs when the application attempts to create temporary files using the mktemp function followed by a safe_fopen function call, but fails to validate that the temporary file was actually created with the appropriate restricted permissions. This race condition allows malicious users to potentially manipulate the file creation process and create files with weak permissions that could be exploited for privilege escalation or information disclosure attacks.
The technical implementation of this vulnerability aligns with CWE-362, which describes a race condition error where two or more processes access shared resources concurrently, leading to unpredictable behavior. In this specific case, the race condition manifests between the temporary file creation and permission verification phases. When the mutt_adv_mktemp function executes, it creates a temporary file using mktemp which generates a unique filename, but the subsequent safe_fopen function call does not adequately verify that the file was created with proper restricted permissions. This gap in validation allows an attacker to potentially create a symbolic link or manipulate the temporary file creation process between the mktemp call and the permission verification, resulting in files with weak permissions that could be exploited.
The operational impact of this vulnerability extends beyond simple permission issues, as it provides local attackers with potential paths for privilege escalation and system compromise. Attackers can exploit this flaw to create temporary files with world-readable or world-writable permissions, potentially allowing them to read sensitive information or inject malicious content into the application's temporary file handling process. This vulnerability particularly affects systems where Mutt is used with elevated privileges, as the weak permissions could enable attackers to access or modify sensitive data that should be restricted. The race condition nature of the vulnerability means that exploitation is possible in environments where multiple processes interact with the same temporary file creation mechanisms, making it a significant concern for server environments and multi-user systems where Mutt is commonly deployed.
Mitigation strategies for CVE-2006-5298 should focus on immediate patching of the Mutt mail client to versions that properly address the race condition in temporary file handling. Organizations should implement comprehensive monitoring of temporary file creation processes and ensure that all temporary files are created with appropriate restrictive permissions immediately upon creation, rather than relying on subsequent verification steps. The solution involves modifying the mutt_adv_mktemp function to enforce proper permission checking immediately after file creation, ensuring that the file is created with restricted permissions before any further processing occurs. Additionally, system administrators should consider implementing file system access controls and monitoring to detect unauthorized changes to temporary file permissions, as well as reviewing and updating security policies for temporary file handling across all applications that may be vulnerable to similar race condition attacks. This vulnerability demonstrates the importance of proper input validation and the need for robust permission checking in all temporary file creation processes, aligning with ATT&CK technique T1059.001 for execution through command-line interfaces and T1078.004 for valid accounts with restricted privileges.