CVE-2009-5023: FAIL2BAN

Medium severity, CVSS 4.7. EPSS: 0.3% chance of exploitation in the next 30 days.

The (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 local users to write to arbitrary files via a symlink attack on temporary files with predictable names, as demonstrated by /tmp/fail2ban-mail.txt.

Affected products

• FAIL2BAN FAIL2BAN: up to and including 0.8.4; version 0.1.0 only; version 0.1.1 only; version 0.1.2 only; version 0.3.0 only; version 0.3.1 only; …

Published 2014-06-10. Last modified 2026-06-16.