CVE-2021-32749

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 "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.

How to fix CVE-2021-32749

To remediate CVE-2021-32749, upgrade the affected package to a fixed version below.

• —upgrade to 0.11.2-r1 or later
• —upgrade to 0.11.2-2 or later

Is CVE-2021-32749 being exploited?

Low — EPSS is 0.3%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 0.11.2-r1
• from 0, < 0.11.2-2

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2021-32749
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-32749