CVE-2010-4345 in Exim
Summary
by MITRE
Exim 4.72 and earlier allows local users to gain privileges by leveraging the ability of the exim user account to specify an alternate configuration file with a directive that contains arbitrary commands, as demonstrated by the spool_directory directive.
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Analysis
by VulDB Data Team • 04/22/2026
The vulnerability identified as CVE-2010-4345 represents a critical privilege escalation flaw in Exim mail transfer agent versions 4.72 and earlier. This security weakness stems from the improper handling of configuration file directives by the exim user account, creating a pathway for local attackers to execute arbitrary commands with elevated privileges. The vulnerability specifically exploits the configuration file parsing mechanism where the exim process can be manipulated to load an alternate configuration file containing malicious directives.
The technical exploitation occurs through the spool_directory directive, which allows the exim user to specify an alternate configuration file that contains arbitrary commands. When Exim processes this directive, it executes the specified commands with the privileges of the exim user, which typically has elevated system access. This creates a direct path for privilege escalation from a local user to a more privileged system account. The flaw exists because the configuration parsing mechanism does not properly validate or sanitize the contents of directives that can be specified by the exim user, allowing command injection through carefully crafted configuration parameters.
The operational impact of this vulnerability is severe as it enables local attackers to gain unauthorized elevated privileges on systems running vulnerable Exim versions. Attackers can leverage this weakness to execute arbitrary code, modify system files, establish persistent access, or escalate privileges to root level access. The vulnerability affects systems where Exim is configured to allow local users to specify alternate configuration files, which is common in many email server implementations. This creates a significant risk for organizations relying on Exim for email services, as local compromise can lead to full system control.
This vulnerability maps to CWE-78 and CWE-20 within the Common Weakness Enumeration framework, specifically addressing command injection flaws and improper input validation in configuration handling. From the MITRE ATT&CK framework perspective, this represents privilege escalation techniques through configuration manipulation and command execution. The attack chain typically involves local user access followed by configuration file manipulation to execute malicious commands. Organizations should implement immediate mitigations including upgrading to Exim version 4.73 or later, which contains the necessary patches to address this vulnerability, and restricting the ability of local users to specify alternate configuration files. Additionally, monitoring for unauthorized configuration file modifications and implementing least privilege principles for Exim user accounts can help reduce the attack surface.