Critical Heap Buffer Overflow in Exim Mail Transfer Agent (CVE‑2010‑4344)
What It Is
A heap‑based buffer overflow resides in the string_vformat function of Exim’s string.c module (versions prior to 4.70). An attacker can craft a malicious SMTP session that overruns the buffer and injects arbitrary code, resulting in remote code execution on the mail server.
Exploitability
The flaw is publicly disclosed with proof‑of‑concept code available and a CVSS v3 base score of 9.8 (Critical). While no large‑scale active campaigns have been confirmed, the remote nature of the attack and the ease of triggering it make the vulnerability highly exploitable.
Affected Products
- Exim Mail Transfer Agent (all releases before 4.70)
Why It Matters for Compliance & Audit Readiness
Remote code execution through a core email service erodes the integrity of inbound/outbound communications—a control required by PCI‑DSS, HIPAA, GDPR, and other frameworks. Demonstrating continuous control monitoring of third‑party software versions, and maintaining a defensible audit trail of patch‑management activities, directly supports vendor‑management and access‑control assurance objectives.
Recommended Actions
- Identify the Exim version on every mail server and upgrade to 4.70 or later.
- If an immediate upgrade is not feasible, apply the vendor’s mitigation patches or temporarily disable the vulnerable functionality.
- Record the remediation in your asset inventory/CMDB and map it to the relevant security control in your governance framework.
- Preserve evidence of the patching activity (e.g., change‑control tickets, logs) to demonstrate due diligence during audits.
Source: https://nvd.nist.gov/vuln/detail/CVE-2010-4344