CVE-2004-0998: Format string vulnerability in telnetd-ssl 0.17 and earlier allows remote attackers to execute arbitrary code.

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HIGH 7.5DOWNGRADEDOWNGRADE

CVE-2004-0998 is a high-severity flaw (CVSS 7.5) affecting telnetd, telnetd-ssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Format string vulnerability in telnetd-ssl 0.17 and earlier allows remote attackers to execute arbitrary code.

Why this priority

High severity
EPSS top 7%: very likely to be exploited

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

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	5.5% (top 7%)
CISA exploited list	No
Published	2004-12-23
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: telnetd

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

Am I affected?

Timeline

2004-12-23 05:00 UTCPublished CVE record published
2026-06-16 22:06 UTCUpdated Record last modified

telnetd telnetd DOWNGRADE

Affected: 0.17.18 · 0.17.25

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.17.18

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.17.18 (Debian / Ubuntu)

apt-cache madison telnetd sudo apt install telnetd=<VERSION_BEFORE_0.17.18> sudo apt-mark hold telnetd

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

dnf --showduplicates list telnetd sudo dnf downgrade telnetd-<VERSION_BEFORE_0.17.18> sudo dnf versionlock add telnetd

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.

telnetd telnetd-ssl DOWNGRADE

Affected: 0.17.17_0.1.1 · 0.17.17_0.1.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.17.17_0.1.1

1. Check installed version

apt-cache policy telnetd-ssl || rpm -q telnetd-ssl || telnetd-ssl --version

2. No fixed release: DOWNGRADE to a release before 0.17.17_0.1.1 (Debian / Ubuntu)

apt-cache madison telnetd-ssl sudo apt install telnetd-ssl=<VERSION_BEFORE_0.17.17_0.1.1> sudo apt-mark hold telnetd-ssl

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

dnf --showduplicates list telnetd-ssl sudo dnf downgrade telnetd-ssl-<VERSION_BEFORE_0.17.17_0.1.1> sudo dnf versionlock add telnetd-ssl

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-2004-0998?

telnetd: downgrade or apply the listed mitigation; telnetd-ssl: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2004-0998 being exploited?

CVE-2004-0998 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-2004-0998 affect?

CVE-2004-0998 affects telnetd, telnetd-ssl. Severity is high (CVSS 7.5). Format string vulnerability in telnetd-ssl 0.17 and earlier allows remote attackers to execute arbitrary code.

How urgent is CVE-2004-0998?

Priority 49/100. High severity; EPSS top 7%: very likely to be exploited

Related CVEs

CVE-2005-2040 MEDIUM 5.0 DOWNGRADE Multiple buffer overflows in the getterminaltype function in telnetd for Heimdal before 0.6.5 may allow remote

References

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