Fail2ban: Denial of Service

1. Gentoo Linux Security Advisory

Package	Vulnerable versions	Unaffected versions	Architecture(s)
net-analyzer/fail2ban	< 0.6.2	>= 0.6.2	All supported architectures

Related bugreports: #157166

A flaw in Fail2ban may allow remote attackers to deny access to arbitrary hosts.

2. Impact Information

Fail2ban monitors log files for failed authentication attempts and can block hosts responsible for repeated attacks.

A flaw in the method used to parse log entries allows remote, unauthenticated attackers to forge authentication attempts from other hosts.

A remote attacker can add arbitrary hosts to the block list, denying legitimate users access to a resource.

3. Resolution Information

There is no known workaround at this time.

All Fail2ban users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-analyzer/fail2ban-0.6.2"

4. References

Updated February 16, 2007

Summary: This is a Gentoo Linux Security Advisory

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