CVE-2021-32749

Summary

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.

Affected Software

VendorProductVersion RangeStatus
fail2banfail2ban<= 0.9.7affected
fail2banfail2ban>= 0.10.0, <= 0.10.6affected
fail2banfail2ban>= 0.11.0, <= 0.11.2affected

Weaknesses

  • CWE-78: CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

ADP Enrichment

CVE Program Container

Additional References

References