CVE-2007-2640: LibTMCG before 1.1.1 does not perform a range check to avoid "trivial group generators," which allows attacker

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HIGH 7.8DOWNGRADE

CVE-2007-2640 is a high-severity flaw (CVSS 7.8) affecting libtmcg. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

LibTMCG before 1.1.1 does not perform a range check to avoid "trivial group generators," which allows attackers to obtain sensitive information about private cards.

Why this priority

High severity

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

Risk facts

CVSS score	7.8 (High)
EPSS exploit chance	1.4% (top 28%)
CISA exploited list	No
Published	2007-05-13
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

2007-05-13 23:19 UTCPublished CVE record published
2026-06-16 22:40 UTCUpdated Record last modified

heiko stamer libtmcg DOWNGRADE

Affected: 1.0 · 1.0.1 · 1.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

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

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

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

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

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

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-2007-2640?

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

Is CVE-2007-2640 being exploited?

CVE-2007-2640 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-2007-2640 affect?

CVE-2007-2640 affects libtmcg. Severity is high (CVSS 7.8). LibTMCG before 1.1.1 does not perform a range check to avoid "trivial group generators," which allows attackers to obtain sensitive information about private cards.

How urgent is CVE-2007-2640?

Priority 45/100. High severity

References

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