Arbitrary Code Injection Affecting fail2ban package, versions <0.11.2-2


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
3.62% (88th percentile)

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  • Snyk IDSNYK-ECHOLATEST-FAIL2BAN-20877239
  • published13 Oct 2026
  • disclosed16 Jul 2021

Introduced: 16 Jul 2021

CVE-2021-32749  (opens in a new tab)
CWE-94  (opens in a new tab)

How to fix?

Upgrade Echo:latest fail2ban to version 0.11.2-2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream fail2ban package and not the fail2ban package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1