CVE-2015-3306: ProFTPD ProFTPD

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

Yes, if you run ProFTPD ProFTPD. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-10-08, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-10-11; treat that as the outer limit, not the target.
EPSS 99.5%, percentile 99.9: FIRST’s model estimates a 99.5% chance of exploitation activity in the next 30 days, higher than 99.9% of all scored CVEs (very high). EPSS is a probability, not a verdict.
Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
Editorial verdict: Check exposure. ProFTPD mod_copy CVE-2015-3306: 2015 Bug Added to KEV — Nearly everyone fixed this a decade ago; the real job is finding any ProFTPD 1.3.5-era build with mod_copy still answering on port 21, usually inside old appliances, and replacing or removing it.

What it is

The modcopy module in ProFTPD 1.3.5 allows remote attackers to read and write to arbitrary files via the site cpfr and site cpto commands.

CISA’s summary

ProFTPD contains an improper access control vulnerability that could allow remote attackers to read and write to arbitrary files via the site cpfr and site cpto commands.

Weakness type: CWE-284.

Product: ProFTPD ProFTPD · Assigned by: mitre · Published: 2015-05-18

Affected and fixed versions

Vendor	Product	Affected versions (per CVE record)
n/a	n/a	see vendor advisory

Severity scores

Scored by	CVSS	Score	Vector
CISA-ADP	3.1	10 Critical	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

Attack vector: network (remotely reachable)
Attack complexity: low
Privileges required: none (no login)
User interaction: none
Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

CISA KEV: added 2026-10-08; federal due date 2026-10-11. Known ransomware use: Unknown.
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.
CISA SSVC assessment: exploitation active, automatable yes, technical impact total.
FIRST EPSS (model of 2026-10-21): 99.50% probability of exploitation activity in the next 30 days; percentile 99.9.

Timeline

2015-05-18 — CVE record published by mitre
2026-10-08 — Added to CISA’s Known Exploited Vulnerabilities catalog
2026-10-08 — erroneo.us brief: ProFTPD mod_copy CVE-2015-3306: 2015 Bug Added to KEV
2026-10-09 — CVE record last updated
2026-10-11 — CISA remediation deadline for US federal agencies

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Other references from the CVE record and advisory

rapid7.com rapid7.com
36803 exploit-db.com
packetstormsecurity.com packetstormsecurity.com
packetstormsecurity.com packetstormsecurity.com
packetstormsecurity.com packetstormsecurity.com
74238 securityfocus.com
36742 exploit-db.com
packetstormsecurity.com packetstormsecurity.com
packetstormsecurity.com packetstormsecurity.com

All exploited ProFTPD vulnerabilities · Today’s Security Digest