CVE-2015-3306
ProFTPD Improper Access Control Vulnerability
ProFTPD ProFTPD
The mod_copy module in ProFTPD 1.3.5 allows remote attackers to read and write to arbitrary files via the site cpfr and site cpto commands.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 8 October 2026. US federal agencies were required to remediate it by 11 October 2026.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 99.5%, which is higher than 99.9% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Frequently asked questions
Is CVE-2015-3306 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2015-3306.
What does CVE-2015-3306 affect?
CVE-2015-3306 affects ProFTPD ProFTPD. The mod_copy module in ProFTPD 1.3.5 allows remote attackers to read and write to arbitrary files via the site cpfr and site cpto commands.
How severe is CVE-2015-3306?
CVE-2015-3306 is rated CRITICAL with a CVSS base score of 10. EPSS puts the probability of exploitation in the next 30 days at 99.5%, higher than 99.9% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 11 October 2026.
How should organisations respond to CVE-2015-3306?
Apply the vendor patch for ProFTPD ProFTPD as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.