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Vulnerability record · CVE-2009-0362 · published 13 February 2009

CVE-2009-0362: Fail2ban improper authentication vulnerability

Fail2ban · Fail2ban

filter.d/wuftpd.conf in Fail2ban 0.8.3 uses an incorrect regular expression that allows remote attackers to cause a denial of service (forced authentication failures) via a crafted reverse-resolved DNS name (rhost) entry that contains a substring that is interpreted as an IP address, a different vulnerability than CVE-2007-4321.

4.0 CVSS 2.0 Medium EPSS 1.3% · top 30.7% CWE-287 · Improper authentication
4.0CVSS 2.0 base score
1.3%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References, 2 tagged exploit
16 Jun 2026Last modified by NVD

Description

filter.d/wuftpd.conf in Fail2ban 0.8.3 uses an incorrect regular expression that allows remote attackers to cause a denial of service (forced authentication failures) via a crafted reverse-resolved DNS name (rhost) entry that contains a substring that is interpreted as an IP address, a different vulnerability than CVE-2007-4321.

AV:N/AC:L/Au:S/C:N/I:N/A:P

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514163 Exploit
http://secunia.com/advisories/33890 Vendor Advisory
http://www.securityfocus.com/bid/33734
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514163 Exploit
http://secunia.com/advisories/33890 Vendor Advisory
http://www.securityfocus.com/bid/33734

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.1CVE-2021-32749Fail2ban os command injection vulnerabilityfail2ban is a daemon to ban hosts that cause multiple authentication errors. In versions 0.9.7 and prior, 0.10.0 through 0.10.6, and 0.11.0 through 0…EPSS 3.6%7.5CVE-2012-5642Fail2ban vulnerabilityserver/action.py in Fail2ban before 0.8.8 does not properly handle the content of the matches tag, which might allow remote attackers to trigger unsa…EPSS 3.1%6.8CVE-2007-4321Fail2ban vulnerabilityfail2ban 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…EPSS 5.7%5.0CVE-2013-7176Fail2ban improper input validation vulnerabilityconfig/filter.d/postfix.conf in the postfix filter in Fail2ban before 0.8.11 allows remote attackers to trigger the blocking of an arbitrary IP addre…EPSS 3.2%5.0CVE-2013-7177Fail2ban improper input validation vulnerabilityconfig/filter.d/cyrus-imap.conf in the cyrus-imap filter in Fail2ban before 0.8.11 allows remote attackers to trigger the blocking of an arbitrary IP…EPSS 3.2%5.0CVE-2013-2178Fail2ban improper input validation vulnerabilityThe apache-auth.conf, apache-nohome.conf, apache-noscript.conf, and apache-overflows.conf files in Fail2ban before 0.8.10 do not properly validate lo…EPSS 1.8%5.0CVE-2006-6302Fail2ban vulnerabilityfail2ban 0.7.4 and earlier does not properly parse sshd log files, which allows remote attackers to add arbitrary hosts to the /etc/hosts.deny file a…EPSS 1.8%4.7CVE-2009-5023Fail2ban link following vulnerabilityThe (1) dshield.conf, (2) mail-buffered.conf, (3) mynetwatchman.conf, and (4) mynetwatchman.conf actions in action.d/ in Fail2ban before 0.8.5 allows…EPSS 0.34%

Source: NIST National Vulnerability Database (record CVE-2009-0362), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.