CVE-2004-2721: The CheckGroup function in openSkat VTMF before 2.1 generates public key pairs in which the "p" variable might

Q: How do I fix CVE-2004-2721?

openskat: upgrade to newer than 2.0. Exact commands for each OS are on this page.

Q: Is CVE-2004-2721 being exploited?

CVE-2004-2721 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-2004-2721 affect?

CVE-2004-2721 affects openskat. Severity is medium (CVSS 4.3). The CheckGroup function in openSkat VTMF before 2.1 generates public key pairs in which the "p" variable might not be prime, which allows remote attackers to determine the private key and decrypt messages.

Q: How urgent is CVE-2004-2721?

Priority 34/100. No elevated risk signals yet.

Routine

MEDIUM 4.3UPGRADE

CVE-2004-2721 is a medium-severity flaw (CVSS 4.3) affecting openskat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The CheckGroup function in openSkat VTMF before 2.1 generates public key pairs in which the "p" variable might not be prime, which allows remote attackers to determine the private key and decrypt messages.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.3 (Medium)
EPSS exploit chance	1.7% (top 23%)
CISA exploited list	No
Weakness	CWE-310
Published	2004-12-31
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: heiko stamer

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

Am I affected?

Timeline

2004-12-31 05:00 UTCPublished CVE record published
2026-06-16 22:10 UTCUpdated Record last modified

heiko stamer openskat UPGRADE

Affected: <= 2.0

Fixed in: newer than 2.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 2.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openskat

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-2004-2721?

openskat: upgrade to newer than 2.0. Exact commands for each OS are on this page.

Is CVE-2004-2721 being exploited?

CVE-2004-2721 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-2004-2721 affect?

CVE-2004-2721 affects openskat. Severity is medium (CVSS 4.3). The CheckGroup function in openSkat VTMF before 2.1 generates public key pairs in which the "p" variable might not be prime, which allows remote attackers to determine the private key and decrypt messages.

How urgent is CVE-2004-2721?

Priority 34/100. No elevated risk signals yet.

References

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