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.
github.com/fail2ban/fail2ban/commit/2ed414ed09b3bb4c478abc9366a1ff22024a33c9
github.com/fail2ban/fail2ban/commit/410a6ce5c80dd981c22752da034f2529b5eee844
github.com/fail2ban/fail2ban/security/advisories/GHSA-m985-3f3v-cwmm
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5WHJK2X2MR2WDYZMCW7COZXJDUSDYMY6/
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZRYQ77MTX5WSV33VCJLK4KBKR55QZ7ZA/
security.gentoo.org/glsa/202310-13