CVE-2021-32749 Possible RCE vulnerability in mailing action using mailutils (mail-whois)
Attackers can execute arbitrary commands via malicious whois responses in fail2ban's mail-whois action, requiring specific configuration.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2021-32749?
CVE-2021-32749 is a medium-severity command injection vulnerability in Fedoraproject Fedora, published on 16 Jul 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2021-32749?
It affects 2 products.
Linux distribution packages (6)
fail2ban SUSE:Package Hub 15 SP1 | All versions | 0.11.2-bp153.2.3.1 |
fail2ban SUSE:Package Hub 15 SP2 | All versions | 0.11.2-bp153.2.3.1 |
fail2ban SUSE:Package Hub 15 SP3 | All versions | 0.11.2-bp153.2.3.1 |
fail2ban openSUSE:Leap 15.2 | All versions | 0.11.2-bp153.2.3.1 |
fail2ban openSUSE:Leap 15.3 | All versions | 0.11.2-bp153.2.3.1 |
fail2ban openSUSE:Tumbleweed | All versions | 0.11.2-3.1 |
Products include Fail2ban Fail2ban, Fedoraproject Fedora.
How do I fix CVE-2021-32749?
Upgrade to a fixed version.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2021-32749 being exploited?
There is no known exploitation of CVE-2021-32749 in the wild and no public exploit code.
Other vulnerabilities in Fedoraproject Fedora
Sources
Also known as ALPINE-CVE-2021-32749, DEBIAN-CVE-2021-32749, GHSA-m985-3f3v-cwmm, MGASA-2021-0464, UBUNTU-CVE-2021-32749, USN-5232-1 and 2 more.