CVE-2021-32749 Information

Description

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 oreign\ 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.

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Reference

https://github.com/fail2ban/fail2ban/commit/410a6ce5c80dd981c22752da034f2529b5eee844 https://github.com/fail2ban/fail2ban/commit/2ed414ed09b3bb4c478abc9366a1ff22024a33c9 https://github.com/fail2ban/fail2ban/security/advisories/GHSA-m985-3f3v-cwmm https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5WHJK2X2MR2WDYZMCW7COZXJDUSDYMY6/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZRYQ77MTX5WSV33VCJLK4KBKR55QZ7ZA/

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

8.1