CVE-2007-4321
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…
Does this matter?
A public exploit is published in Exploit-DB (verified), so the technical barrier is gone even though the severity is medium and EPSS is 5.7%. Treat it as high on anything reachable from the internet.
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.
- CVSS 2.0
- 6.8 MEDIUMAV:N/AC:M/Au:N/C:P/I:P/A:P
- EPSS
- 5.75% probability · 93th percentile
- Public exploits
- 1 in Exploit-DB · verified · first 28 July 2007
- CISA KEV
- Not listed
- Affected
- fail2ban/fail2ban
- Source
- cve@mitre.org
EPSS 5.7% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- http://bugs.gentoo.org/show_bug.cgi?id=181214
- http://osvdb.org/42484
- http://secunia.com/advisories/23237
- http://secunia.com/advisories/28374
- http://security.gentoo.org/glsa/glsa-200707-13.xml
- http://www.debian.org/security/2008/dsa-1456
- http://www.ossec.net/en/attacking-loganalysis.html
- http://www.securityfocus.com/bid/25117
- http://bugs.gentoo.org/show_bug.cgi?id=181214
- http://osvdb.org/42484
- http://secunia.com/advisories/23237
- http://secunia.com/advisories/28374
- http://security.gentoo.org/glsa/glsa-200707-13.xml
- http://www.debian.org/security/2008/dsa-1456
- http://www.ossec.net/en/attacking-loganalysis.html
- http://www.securityfocus.com/bid/25117
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.