CVE-2021-32749

Published: 16 July 2021

fail2ban 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 0.11.2, there is a vulnerability that leads to possible remote code execution in the mailing action mail-whois. Command `mail` from mailutils package used in mail actions like `mail-whois` can execute command if unescaped sequences (`\n~`) are available in "foreign" input (for instance in whois output). To exploit the vulnerability, an attacker would need to insert malicious characters into the response sent by the whois server, either via a MITM attack or by taking over a whois server. The issue is patched in versions 0.10.7 and 0.11.3. As a workaround, one may avoid the usage of action `mail-whois` or patch the vulnerability manually.

Priority

Medium

CVSS 3 base score: 8.1

Status

Package Release Status
fail2ban
Launchpad, Ubuntu, Debian
Upstream
Released (0.11.2-2)
Ubuntu 21.10 (Impish Indri) Not vulnerable
(0.11.2-2)
Ubuntu 21.04 (Hirsute Hippo) Needed

Ubuntu 20.04 LTS (Focal Fossa) Needed

Ubuntu 18.04 LTS (Bionic Beaver) Needed

Ubuntu 16.04 ESM (Xenial Xerus) Ignored
(out of standard support)
Ubuntu 14.04 ESM (Trusty Tahr) Needed