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How CVE-2025-43920 Works
GNU Mailman 2.1.39, when integrated with cPanel/WHM and configured with external archivers, fails to sanitize email Subject fields. Attackers inject shell metacharacters (e.g., ;, |, &) in Subject lines, which are passed unsanitized to shell commands during archiving. This allows arbitrary command execution under Mailman’s process privileges. The vulnerability stems from improper input validation when invoking external archiver scripts.
DailyCVE Form
Platform: cPanel/WHM
Version: GNU Mailman 2.1.39
Vulnerability: Command Injection
Severity: Critical
Date: 04/24/2025
What Undercode Say:
Exploitation
Craft malicious email with Subject payload sendmail -t <<EOF To: [email protected] Subject: ; rm -rf /var/www/html; EOF
Detection
Check Mailman version grep "VERSION" /usr/lib/mailman/Mailman/Version.py Audit archiver configurations cat /etc/mailman/mm_cfg.py | grep "ARCHIVE"
Mitigation
Patch example: Sanitize Subject in archiver.py import shlex def sanitize_subject(subject): return shlex.quote(subject)
Analytics
- Attack Vector: Network (email)
- Privilege Required: None
- User Interaction: Not needed
- CVSS 4.0: 9.8 (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H)
Protection
WAF rule to block metacharacters SecRule ARGS:Subject "@contains ;" "deny,log,id:10043920"
Immediate workaround chmod -R 750 /usr/lib/mailman/scripts
Log Analysis
Monitor Mailman logs for exploitation attempts grep -E ';|||&' /var/log/mailman/
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
