CVE-2010-4344VulnerabilityPublished 03/25/2022Updated 10/24/2026

CVE-2010-4344: Exim Heap-Based Buffer Overflow Vulnerability

Affects Exim EximSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 03/25/2022
KEV deadline: 04/15/2022
EPSS: 71.7% chance of exploitation in 30 days – higher than 99% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2010-4344 (opens in a new tab)

Affected software

Product	Affected	Fixed in
Exim Exim	Affected <4.70	Fixed in–

Description

CVE-2010-4344 is a heap-based buffer overflow vulnerability in the string_vformat function of Exim mail transfer agent versions before 4.70. This flaw allows remote attackers to execute arbitrary code during an SMTP session. The vulnerability has been exploited in the wild, indicating active threat usage. No explicit patch links are provided in the input data, and affected versions are not specifically enumerated beyond 'before 4.70'.

Summary

The vulnerability CVE-2010-4344 exists in Exim versions prior to 4.70, specifically in the string_vformat function within string.c. It is a heap-based buffer overflow that can be triggered remotely via an SMTP session, enabling attackers to execute arbitrary code on the affected system. This vulnerability has been observed to be exploited in the wild, increasing its risk profile. The input data does not provide explicit patch information or vendor advisory details.

Impact

Successful exploitation of this vulnerability allows remote attackers to execute arbitrary code on the affected Exim server, potentially leading to full system compromise. Given that it is exploitable remotely via SMTP, it poses a significant risk to mail servers running vulnerable versions. The presence of known exploits in the wild confirms active exploitation attempts.

Mitigation

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since the vulnerability affects Exim versions before 4.70, upgrading to version 4.70 or later is recommended if confirmed by vendor sources. Until official guidance is obtained, restrict access to SMTP services and monitor for suspicious activity related to Exim.

Weaknesses

CWE-119Buffer Errors (Memory Bounds) (opens in a new tab)

What to do

Affected software

Description

AnalysisAI-generated, updated 10/24/2026, 10:55:52 UTC

Weaknesses

References

Related threats