CVE-2025-30232: Critical Use-After-Free Vulnerability in Exim 4.96 to 4.98.1

Overview

In the constantly evolving field of cybersecurity, it’s crucial to stay updated with recent vulnerabilities. One such critical vulnerability has been identified in Exim versions 4.96 through 4.98.1, a widely used mail transfer agent (MTA). Identified as CVE-2025-30232, this vulnerability is a use-after-free error that could potentially allow users with command-line access to escalate their privileges. Given Exim’s popularity, this vulnerability could have far-reaching implications, affecting numerous businesses and systems worldwide.

Vulnerability Summary

CVE ID: CVE-2025-30232
Severity: Critical, CVSS score 8.1
Attack Vector: Local
Privileges Required: Low
User Interaction: Required
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

Exim | 4.96 through 4.98.1

How the Exploit Works

The CVE-2025-30232 vulnerability arises from a use-after-free error in Exim. This error allows an attacker with command-line access to manipulate memory management and escalate their privileges. The attacker can execute arbitrary code with escalated privileges, allowing them to compromise the system or potentially exfiltrate data.

Conceptual Example Code

Here’s a conceptual example of how this vulnerability might be exploited from the command line:

$ exim -bd -C'acl_smtp_data = ${run{${substr{0}{1}{$spool_directory}}}}'

In this conceptual example, we see an attacker using the Exim command-line interface to exploit the use-after-free vulnerability. The attacker manipulates Exim’s configuration to execute arbitrary code with escalated privileges.

Mitigation

To mitigate this vulnerability, users are strongly advised to apply the patch provided by the vendor as soon as possible. If applying the patch is not feasible in the immediate term, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can provide temporary mitigation. However, these should not be considered long-term solutions as they may not fully prevent exploitation of this vulnerability. It is always best practice to apply patches and updates promptly to ensure system security.