CVE-2007-4440: Stack-based buffer overflow in the MercuryS SMTP server in Mercury Mail Transport System, possibly 4.51 and ea

Q: How do I fix CVE-2007-4440?

mercury mail transport system: upgrade to newer than 4.51. Exact commands for each OS are on this page.

Q: Is CVE-2007-4440 being exploited?

CVE-2007-4440 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2007-4440 affect?

CVE-2007-4440 affects mercury mail transport system. Severity is high (CVSS 7.5). Stack-based buffer overflow in the MercuryS SMTP server in Mercury Mail Transport System, possibly 4.51 and earlier, allows remote attackers to execute arbitrary code via a long AUTH CRAM-MD5 string. NOTE: this might overlap CVE-2006-5961.

Q: How urgent is CVE-2007-4440?

Priority 56/100. High severity; EPSS top 1%: very likely to be exploited; Public exploit reference

This week

HIGH 7.5UPGRADE

CVE-2007-4440 is a high-severity flaw (CVSS 7.5) affecting mercury mail transport system. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Stack-based buffer overflow in the MercuryS SMTP server in Mercury Mail Transport System, possibly 4.51 and earlier, allows remote attackers to execute arbitrary code via a long AUTH CRAM-MD5 string. NOTE: this might overlap CVE-2006-5961.

Why this priority

High severity
EPSS top 1%: very likely to be exploited
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	64.5% (top 1%)
CISA exploited list	No
Weakness	CWE-119
Published	2007-08-21
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: pmail

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2007-08-21 00:17 UTCPublished CVE record published
2026-06-16 22:44 UTCUpdated Record last modified

pmail mercury mail transport system UPGRADE

Affected: <= 4.51

Fixed in: newer than 4.51

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy mercury-mail-transport-system || rpm -q mercury-mail-transport-system || mercury-mail-transport-system --version

2. UPGRADE to newer than 4.51 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mercury-mail-transport-system

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mercury-mail-transport-system

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Mercury/32 Mail SMTPD - Remote Stack Overrun (PoC)
Exploit-DB: Mercury/32 Mail SMTPD - AUTH CRAM-MD5 Buffer Overflow (Metasploit)
Exploit-DB: Mercury/32 Mail SMTPD 4.51 - SMTPD CRAM-MD5 Remote Overflow
Metasploit: Mercury Mail SMTP AUTH CRAM-MD5 Buffer Overflow

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2007-4440?

mercury mail transport system: upgrade to newer than 4.51. Exact commands for each OS are on this page.

Is CVE-2007-4440 being exploited?

CVE-2007-4440 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2007-4440 affect?

CVE-2007-4440 affects mercury mail transport system. Severity is high (CVSS 7.5). Stack-based buffer overflow in the MercuryS SMTP server in Mercury Mail Transport System, possibly 4.51 and earlier, allows remote attackers to execute arbitrary code via a long AUTH CRAM-MD5 string. NOTE: this might overlap CVE-2006-5961.

How urgent is CVE-2007-4440?

Priority 56/100. High severity; EPSS top 1%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2007-1373 HIGH 10.0 UPGRADE Stack-based buffer overflow in Mercury/32 (aka Mercury Mail Transport System) 4.01b and earlier allows remote
CVE-2006-5961 HIGH 7.5 DOWNGRADE Buffer overflow in Mercury Mail Transport System 4.01b for Windows has unknown impact and attack vectors, as o
CVE-2005-4411 HIGH 7.5 DOWNGRADE Buffer overflow in Mercury Mail Transport System 4.01b allows remote attackers to execute arbitrary code via a

References

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