CVE-2005-2991: ncompress 4.2.4 and earlier allows local users to overwrite arbitrary files via a symlink attack on temporary

Q: How do I fix CVE-2005-2991?

ncompress: upgrade to newer than 4.2.4_r1. Exact commands for each OS are on this page.

Q: Is CVE-2005-2991 being exploited?

CVE-2005-2991 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2005-2991 affect?

CVE-2005-2991 affects ncompress. Severity is low (CVSS 2.1). ncompress 4.2.4 and earlier allows local users to overwrite arbitrary files via a symlink attack on temporary files using (1) zdiff or (2) zcmp, a different vulnerability than CVE-2004-0970.

Q: How urgent is CVE-2005-2991?

Priority 15/100. No elevated risk signals yet.

Routine

LOW 2.1UPGRADE

CVE-2005-2991 is a low-severity flaw (CVSS 2.1) affecting ncompress. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ncompress 4.2.4 and earlier allows local users to overwrite arbitrary files via a symlink attack on temporary files using (1) zdiff or (2) zcmp, a different vulnerability than CVE-2004-0970.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	2.1 (Low)
EPSS exploit chance	0.4% (top 69%)
CISA exploited list	No
Published	2005-09-20
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: ncompress

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

Am I affected?

Timeline

2005-09-20 20:03 UTCPublished CVE record published
2026-06-16 22:16 UTCUpdated Record last modified

ncompress ncompress UPGRADE

Affected: <= 4.2.4_r1

Fixed in: newer than 4.2.4_r1

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 4.2.4_r1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ncompress

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ncompress

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2005-2991?

ncompress: upgrade to newer than 4.2.4_r1. Exact commands for each OS are on this page.

Is CVE-2005-2991 being exploited?

CVE-2005-2991 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-2005-2991 affect?

CVE-2005-2991 affects ncompress. Severity is low (CVSS 2.1). ncompress 4.2.4 and earlier allows local users to overwrite arbitrary files via a symlink attack on temporary files using (1) zdiff or (2) zcmp, a different vulnerability than CVE-2004-0970.

How urgent is CVE-2005-2991?

Priority 15/100. No elevated risk signals yet.

Related CVEs

CVE-2006-1168 HIGH 7.5 DOWNGRADE The decompress function in compress42.c in (1) ncompress 4.2.4 and (2) liblzw allows remote attackers to cause
CVE-2001-1413 HIGH 7.5 UPGRADE Stack-based buffer overflow in the comprexx function for ncompress 4.2.4 and earlier, when used in situations

References

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