CVE-2001-0894: Vulnerability in Postfix SMTP server before 20010228-pl07, when configured to email the postmaster when SMTP e

Routine

MEDIUM 5.0DOWNGRADE

CVE-2001-0894 is a medium-severity flaw (CVSS 5.0) affecting postfix. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Vulnerability in Postfix SMTP server before 20010228-pl07, when configured to email the postmaster when SMTP errors cause the session to terminate, allows remote attackers to cause a denial of service (memory exhaustion) by generating a large number of SMTP errors, which forces the SMTP session log to grow too large.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	1.9% (top 20%)
CISA exploited list	No
Published	2001-11-11
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: wietse venema

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

Am I affected?

Timeline

2001-11-11 05:00 UTCPublished CVE record published
2026-06-16 21:55 UTCUpdated Record last modified

wietse venema postfix DOWNGRADE

Affected: 1999-09-06 · 1999-12-31 · 2000-02-28

Fixed in: no fixed release known

Safe to downgrade to: a release before 1999-09-06

1. Check installed version

apt-cache policy postfix || rpm -q postfix || postfix --version

2. No fixed release: DOWNGRADE to a release before 1999-09-06 (Debian / Ubuntu)

apt-cache madison postfix sudo apt install postfix=<VERSION_BEFORE_1999-09-06> sudo apt-mark hold postfix

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list postfix sudo dnf downgrade postfix-<VERSION_BEFORE_1999-09-06> sudo dnf versionlock add postfix

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2001-0894?

postfix: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2001-0894 being exploited?

CVE-2001-0894 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-2001-0894 affect?

CVE-2001-0894 affects postfix. Severity is medium (CVSS 5.0). Vulnerability in Postfix SMTP server before 20010228-pl07, when configured to email the postmaster when SMTP errors cause the session to terminate, allows remote attackers to cause a denial of service (memory exhaustion) by generating a lar

How urgent is CVE-2001-0894?

Priority 37/100. No elevated risk signals yet.

Software pages

Postfix vulnerabilities

Related CVEs

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CVE-2026-43964 LOW 3.7 UPGRADE Postfix before 3.8.16, 3.9 before 3.9.10, and 3.10 before 3.10.9 sometimes allows a buffer over-read and proce
CVE-2020-12063 MEDIUM 5.3 DOWNGRADE A certain Postfix 2.10.1-7 package could allow an attacker to send an email from an arbitrary-looking sender v
CVE-2017-10140 HIGH 7.8 UPGRADE Postfix before 2.11.10, 3.0.x before 3.0.10, 3.1.x before 3.1.6, and 3.2.x before 3.2.2 might allow local user
CVE-2012-0811 MEDIUM 6.5 UPGRADE Multiple SQL injection vulnerabilities in Postfix Admin (aka postfixadmin) before 2.3.5 allow remote authentic

References

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