CVE-2005-1600: A "mathematical flaw" in the implementation of the El Gamal signature algorithm for LibTomCrypt 1.0 to 1.0.2 a

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HIGH 7.5DOWNGRADE

CVE-2005-1600 is a high-severity flaw (CVSS 7.5) affecting libtomcrypt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A "mathematical flaw" in the implementation of the El Gamal signature algorithm for LibTomCrypt 1.0 to 1.0.2 allows attackers to generate valid signatures without having the private key.

Why this priority

High severity

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

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	1.5% (top 26%)
CISA exploited list	No
Published	2005-05-16
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: libtomcrypt

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

Am I affected?

Timeline

2005-05-16 04:00 UTCPublished CVE record published
2026-06-16 22:13 UTCUpdated Record last modified

libtomcrypt libtomcrypt DOWNGRADE

Affected: 1.0 · 1.0.1 · 1.0.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.0 (Debian / Ubuntu)

apt-cache madison libtomcrypt sudo apt install libtomcrypt=<VERSION_BEFORE_1.0> sudo apt-mark hold libtomcrypt

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

dnf --showduplicates list libtomcrypt sudo dnf downgrade libtomcrypt-<VERSION_BEFORE_1.0> sudo dnf versionlock add libtomcrypt

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-2005-1600?

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

Is CVE-2005-1600 being exploited?

CVE-2005-1600 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-2005-1600 affect?

CVE-2005-1600 affects libtomcrypt. Severity is high (CVSS 7.5). A "mathematical flaw" in the implementation of the El Gamal signature algorithm for LibTomCrypt 1.0 to 1.0.2 allows attackers to generate valid signatures without having the private key.

How urgent is CVE-2005-1600?

Priority 45/100. High severity

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References

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