ProFTPD is affected by CVE-2015-3306, rated 10 (critical). CISA lists it as a Known Exploited Vulnerability, added on 2026-10-08, which means attacks against it have been observed.
What the flaw is
The NIST National Vulnerability Database describes it as follows:
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.
At a glance
| Field | Detail |
|---|---|
| CVE | CVE-2015-3306 |
| Affected product | ProFTPD |
| Weakness | CWE-284 (Access Control) |
| CVSS | 10 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| Added to CISA KEV | 2026-10-08 |
| Federal remediation due | 2026-10-11 |
| Known ransomware use | Unknown |
What defenders should do
- CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- Patch: apply the fixed release from ProFTPD; check the vendor advisory linked below for the exact versions.
- Inventory: identify every instance of ProFTPD, prioritising internet-facing ones.
- Hunt: review access and application logs on exposed instances for activity predating the patch, and treat unpatched internet-facing instances as potentially compromised.
