CVE-2004-0623: Format string vulnerability in misc.c in GNU GNATS 4.00 may allow remote attackers to execute arbitrary code v

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HIGH 10.0DOWNGRADE

CVE-2004-0623 is a high-severity flaw (CVSS 10.0) affecting gnats. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Format string vulnerability in misc.c in GNU GNATS 4.00 may allow remote attackers to execute arbitrary code via format string specifiers in a string that gets logged by syslog.

Why this priority

Critical severity
EPSS top 9%: very likely to be exploited

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

Risk facts

CVSS score	10.0 (High)
EPSS exploit chance	4.5% (top 9%)
CISA exploited list	No
Published	2004-12-06
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: gnu

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

Am I affected?

Timeline

2004-12-06 05:00 UTCPublished CVE record published
2026-06-16 22:06 UTCUpdated Record last modified

gnu gnats DOWNGRADE

Affected: 3.0_02 · 3.2 · 3.14b · 3.113 · 3.113.1 · 3.113.1.6 · 4.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.0_02

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.0_02 (Debian / Ubuntu)

apt-cache madison gnats sudo apt install gnats=<VERSION_BEFORE_3.0_02> sudo apt-mark hold gnats

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

dnf --showduplicates list gnats sudo dnf downgrade gnats-<VERSION_BEFORE_3.0_02> sudo dnf versionlock add gnats

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-2004-0623?

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

Is CVE-2004-0623 being exploited?

CVE-2004-0623 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-2004-0623 affect?

CVE-2004-0623 affects gnats. Severity is high (CVSS 10.0). Format string vulnerability in misc.c in GNU GNATS 4.00 may allow remote attackers to execute arbitrary code via format string specifiers in a string that gets logged by syslog.

How urgent is CVE-2004-0623?

Priority 58/100. Critical severity; EPSS top 9%: very likely to be exploited

Related CVEs

CVE-2007-2808 MEDIUM 4.3 DOWNGRADE DOWNGRADE Cross-site scripting (XSS) vulnerability in gnatsweb.pl in Gnatsweb 4.00 and Gnats 4.1.99 allows remote attack
CVE-2005-2180 LOW 2.1 DOWNGRADE gen-index in GNATS 4.0, 4.1.0, and possibly earlier versions, when installed setuid, does not properly check f

References

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