CVE-1999-0001: ip_input.c in BSD-derived TCP/IP implementations allows remote attackers to cause a denial of service (crash o

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MEDIUM 5.0MITIGATEMITIGATEMITIGATE

CVE-1999-0001 is a medium-severity flaw (CVSS 5.0) affecting bsd os, freebsd, openbsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ip_input.c in BSD-derived TCP/IP implementations allows remote attackers to cause a denial of service (crash or hang) via crafted packets.

Why this priority

EPSS top 8%: very likely to be exploited

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	4.8% (top 8%)
CISA exploited list	No
Weakness	CWE-20
Published	1999-12-30
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: bsdi · freebsd · openbsd

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

Am I affected?

Timeline

1999-12-30 05:00 UTCPublished CVE record published
2026-06-16 21:47 UTCUpdated Record last modified

bsdi bsd os MITIGATE

Affected: 3.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.1

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

freebsd freebsd MITIGATE

Affected: 1.0 · 1.1 · 1.1.5.1 · 1.2 · 2.0 · 2.0.1 · 2.0.5 · 2.1.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

openbsd openbsd MITIGATE

Affected: 2.3 · 2.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.3

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-1999-0001?

bsd os: mitigate or apply the listed mitigation; freebsd: mitigate or apply the listed mitigation; openbsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-1999-0001 being exploited?

CVE-1999-0001 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-1999-0001 affect?

CVE-1999-0001 affects bsd os, freebsd, openbsd. Severity is medium (CVSS 5.0). ip_input.c in BSD-derived TCP/IP implementations allows remote attackers to cause a denial of service (crash or hang) via crafted packets.

How urgent is CVE-1999-0001?

Priority 40/100. EPSS top 8%: very likely to be exploited

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References

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