Rapid7 Vulnerability & Exploit Database

Ubuntu: USN-5232-1 (CVE-2021-32749): Fail2ban vulnerability

Free InsightVM Trial No Credit Card Necessary
Watch Demo See how it all works
Back to Search

Ubuntu: USN-5232-1 (CVE-2021-32749): Fail2ban vulnerability

Severity
7
CVSS
(AV:N/AC:M/Au:N/C:P/I:P/A:P)
Published
07/16/2021
Created
03/29/2023
Added
03/22/2023
Modified
03/22/2023

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.

Solution(s)

  • ubuntu-upgrade-fail2ban

With Rapid7 live dashboards, I have a clear view of all the assets on my network, which ones can be exploited, and what I need to do in order to reduce the risk in my environment in real-time. No other tool gives us that kind of value and insight.

– Scott Cheney, Manager of Information Security, Sierra View Medical Center

;