CVE-2006-2421: Stack-based buffer overflow in Pragma FortressSSH 4.0.7.20 allows remote attackers to execute arbitrary code v

Q: How do I fix CVE-2006-2421?

fortressssh: upgrade to newer than 4.0.7.20. Exact commands for each OS are on this page.

Q: Is CVE-2006-2421 being exploited?

CVE-2006-2421 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-2006-2421 affect?

CVE-2006-2421 affects fortressssh. Severity is high (CVSS 7.5). Stack-based buffer overflow in Pragma FortressSSH 4.0.7.20 allows remote attackers to execute arbitrary code via long SSH_MSG_KEXINIT messages, which may cause an overflow when being logged. NOTE: the provenance of this information is unkn

This month

HIGH 7.5UPGRADE

CVE-2006-2421 is a high-severity flaw (CVSS 7.5) affecting fortressssh. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Stack-based buffer overflow in Pragma FortressSSH 4.0.7.20 allows remote attackers to execute arbitrary code via long SSH_MSG_KEXINIT messages, which may cause an overflow when being logged. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	3.2% (top 12%)
CISA exploited list	No
Published	2006-05-17
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: pragma systems

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

Am I affected?

Timeline

2006-05-17 10:06 UTCPublished CVE record published
2026-06-16 22:24 UTCUpdated Record last modified

pragma systems fortressssh UPGRADE

Affected: <= 4.0.7.20

Fixed in: newer than 4.0.7.20

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 4.0.7.20 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fortressssh

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-2006-2421?

fortressssh: upgrade to newer than 4.0.7.20. Exact commands for each OS are on this page.

Is CVE-2006-2421 being exploited?

CVE-2006-2421 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-2006-2421 affect?

CVE-2006-2421 affects fortressssh. Severity is high (CVSS 7.5). Stack-based buffer overflow in Pragma FortressSSH 4.0.7.20 allows remote attackers to execute arbitrary code via long SSH_MSG_KEXINIT messages, which may cause an overflow when being logged. NOTE: the provenance of this information is unkn

How urgent is CVE-2006-2421?

Priority 48/100. High severity

References

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