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TI-2021-12417 Aliases CVE-2021-32749

Possible RCE vulnerability in mailing action using mailutils (mail-whois)

Priority MEDIUM 41CWE-78Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-78.

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.

Why it matters now

EPSS 0.03428 89th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
fail2banfail2banup to 0.9.7; 0.10.0 – 0.10.6; 0.11.0 – 0.11.2—No fix listedCNA
  • fail2ban Vendorfail2ban Affected up to 0.9.7; 0.10.0 – 0.10.6; 0.11.0 – 0.11.2 Fixed in — No fix listed CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:fail2ban:fail2ban:*:*:*:*:*:*:*:*up to 0.9.7; 0.10.0 to before 0.10.7; 0.11.0 to before 0.11.3Vulnerablefail2ban
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*34VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*35VulnerableFedoraproject
  • cpe:2.3:a:fail2ban:fail2ban:*:*:*:*:*:*:*:* Versions up to 0.9.7; 0.10.0 to before 0.10.7; 0.11.0 to before 0.11.3 Vulnerable ·fail2ban
  • cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-32749

References

Exploit 1

Patch 2

Advisory 3

  • TI-2007-04181 fail2ban 0.8 and earlier does not properly parse sshd log files, which allows remote… CVSS 2.0MEDIUM 6.8
  • TI-2012-04743 server/action.py in Fail2ban before 0.8.8 does not properly handle the content of the… CVSS 2.0HIGH 7.5
  • TI-2013-05868 config/filter.d/cyrus-imap.conf in the cyrus-imap filter in Fail2ban before 0.8.11 allows… CVSS 2.0MEDIUM 5.0
  • TI-2013-05867 config/filter.d/postfix.conf in the postfix filter in Fail2ban before 0.8.11 allows… CVSS 2.0MEDIUM 5.0
  • TI-2013-01945 The apache-auth.conf, apache-nohome.conf, apache-noscript.conf, and apache-overflows.conf… CVSS 2.0MEDIUM 5.0
  • TI-2006-06066 fail2ban 0.7.4 and earlier does not properly parse sshd log files, which allows remote… CVSS 2.0MEDIUM 5.0
See all 8 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences