CVE-2025-30232 in Exim
Summary
by MITRE • 03/28/2025
A use-after-free in Exim 4.96 through 4.98.1 could allow users (with command-line access) to escalate privileges.
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Analysis
by VulDB Data Team • 10/01/2025
The vulnerability identified as CVE-2025-30232 represents a critical use-after-free condition affecting Exim email transfer agent versions 4.96 through 4.98.1. This flaw exists within the mail processing subsystem where improper memory management allows for potential privilege escalation. The vulnerability specifically manifests when users with command-line access can exploit the memory corruption to gain elevated system privileges, making it particularly dangerous in multi-user environments where Exim operates with elevated permissions.
The technical root cause of this vulnerability stems from improper handling of memory allocation and deallocation within Exim's processing functions. When certain mail processing operations complete, memory blocks are freed but references to these locations persist in the application's execution flow. This creates a window where malicious input can manipulate the freed memory, potentially leading to arbitrary code execution. The flaw falls under CWE-416 which specifically addresses use-after-free vulnerabilities where memory is accessed after it has been freed, and aligns with ATT&CK technique T1068 which covers privilege escalation through local exploits.
The operational impact of this vulnerability extends beyond simple privilege escalation as it can enable attackers to gain root access to systems running affected Exim versions. This poses significant risk to email servers, particularly those configured with setuid root permissions or running with elevated privileges. Attackers can leverage this vulnerability by crafting malicious email messages or manipulating command-line parameters that trigger the vulnerable code path. The exploitation requires only command-line access, making it particularly concerning for systems where users have shell access but should not possess elevated privileges.
Mitigation strategies for CVE-2025-30232 should prioritize immediate patching of Exim installations to versions that address the memory management issues. Organizations should also implement strict access controls limiting command-line access to privileged users only and consider running Exim with reduced privileges where possible. Network segmentation and monitoring for unusual command-line activity can help detect potential exploitation attempts. Additionally, implementing proper input validation and sanitization measures for mail processing can reduce the attack surface. System administrators should also conduct thorough vulnerability assessments to identify any other instances of similar memory management issues within the email infrastructure and consider implementing runtime protection mechanisms to detect memory corruption attempts.