CVE-2000-0556: Buffer overflow in the web interface for Cmail 2.4.7 allows remote attackers to cause a denial of service by s

Routine

MEDIUM 5.0DOWNGRADE

CVE-2000-0556 is a medium-severity flaw (CVSS 5.0) affecting cmail. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Buffer overflow in the web interface for Cmail 2.4.7 allows remote attackers to cause a denial of service by sending a large user name to the user dialog running on port 8002.

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 21%)
CISA exploited list	No
Published	2000-06-05
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: computalynx

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

Am I affected?

Timeline

2000-06-05 04:00 UTCPublished CVE record published
2026-06-16 21:51 UTCUpdated Record last modified

computalynx cmail DOWNGRADE

Affected: 2.4.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.4.7

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.4.7 (Debian / Ubuntu)

apt-cache madison cmail sudo apt install cmail=<VERSION_BEFORE_2.4.7> sudo apt-mark hold cmail

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

dnf --showduplicates list cmail sudo dnf downgrade cmail-<VERSION_BEFORE_2.4.7> sudo dnf versionlock add cmail

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-2000-0556?

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

Is CVE-2000-0556 being exploited?

CVE-2000-0556 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-2000-0556 affect?

CVE-2000-0556 affects cmail. Severity is medium (CVSS 5.0). Buffer overflow in the web interface for Cmail 2.4.7 allows remote attackers to cause a denial of service by sending a large user name to the user dialog running on port 8002.

How urgent is CVE-2000-0556?

Priority 37/100. No elevated risk signals yet.

Related CVEs

CVE-2001-0742 HIGH 7.5 DOWNGRADE Buffer overflow in Computalynx CMail POP3 mail server 2.4.9 allows remote attackers to run arbitrary code via
CVE-2000-0557 HIGH 10.0 DOWNGRADE Buffer overflow in the web interface for Cmail 2.4.7 allows remote attackers to execute arbitrary commands via
CVE-1999-1521 HIGH 10.0 DOWNGRADE Computalynx CMail 2.4 and CMail 2.3 SP2 SMTP servers are vulnerable to a buffer overflow attack in the MAIL FR

References

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