mod_sql in ProFTPD before 1.3.9a allows remote attackers to execute arbitrary code via a username, in scenarios where there is logging of USER requests with an expansion such as %U, and the SQL backend allows commands (e.g., COPY TO PROGRAM).

References

• http://www.proftpd.org/docs/RELEASE_NOTES-1.3.10rc1
• https://github.com/ZeroPathAI/proftpd-CVE-2026-42167-poc
• https://github.com/proftpd/proftpd/issues/2052
• https://www.openwall.com/lists/oss-security/2026/05/01/4
• https://zeropath.com/blog/proftpd-cve-2026-42167-auth-bypass-privesc-rce
• http://www.openwall.com/lists/oss-security/2026/05/01/13
• http://www.openwall.com/lists/oss-security/2026/05/01/4
• https://github.com/ZeroPathAI/proftpd-CVE-2026-42167-poc