Is CVE-2007-4321 in the CISA KEV catalog?

No. CVE-2007-4321 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2007-4321?

CVE-2007-4321 has a CVSS v2 base score of 6.8 (MEDIUM).

What is the EPSS score for CVE-2007-4321?

CVE-2007-4321 has an EPSS score of 5.75% (92th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2007-4321?

Upgrade fail2ban on debian 11 to 0.8.0-4 or later.

CVE & CISA-KEV Catalog

CVE-2007-4321

MEDIUMEPSS 92th pctl

6.8

CVSS v2

NVD

Description

fail2ban 0.8 and earlier does not properly parse sshd log files, which allows remote attackers to add arbitrary hosts to the /etc/hosts.deny file and cause a denial of service by adding arbitrary IP addresses to the sshd log file, as demonstrated by logging in via ssh with a client protocol version identification containing an IP address string, a different vector than CVE-2006-6302.

How to fix

Remediation Available

fail2banDebian

Fixed in:0.8.0-4CVE-2007-4321

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v2 Vector

No CVSS vector data available.

Exploit Intelligence

5.75%probability of exploitation in 30 days

92ndpercentile

High risk: more likely to be exploited than 92% of all known CVEs.

References

Other references8

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-23.