CVE-2015-3306

ProFTPD exploited vulnerability, confirmed exploited in the wild.

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.

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99%chance of exploitation in the next 30 days (EPSS), 99th percentile

8 Octadded to CISA's Known Exploited Vulnerabilities list, 2026

11 Octfederal remediation deadline, already passed

Passedpast the deadline: patch now

CISA's name for it	ProFTPD Improper Access Control Vulnerability
Vendor and product	ProFTPD · ProFTPD
Type	exploited vulnerability · CWE-284
Exploited	Confirmed by CISA listed 8 October 2026
Likelihood	one of the most likely to be exploited of every vulnerability tracked
Deadline	11 October 2026 · already passed
Used in ransomware	Not reported
Advisories	lists.debian.org ↗ · lists.opensuse.org ↗ · www.cisa.gov ↗ · www.cisa.gov ↗

What to do

Three steps, in this order

Step 1

Apply the vendor's fix or mitigation; CISA lists only vulnerabilities seen exploited.

Step 2

If you cannot patch now, restrict network access to the affected product.

Step 3

Check for signs of compromise since the date it was added to the list.

CISA's 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's 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.

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Questions

CVE-2015-3306 in short

Is CVE-2015-3306 being exploited?

Yes. CISA added CVE-2015-3306 to its Known Exploited Vulnerabilities catalogue on 8 October 2026, which it does only on evidence of exploitation in the wild.

What is the CISA deadline for CVE-2015-3306?

US federal agencies must remediate it by 11 October 2026. Everyone else should treat that date as the latest safe point to patch an internet-facing system.

How likely is CVE-2015-3306 to be exploited in the next 30 days?

FIRST's Exploit Prediction Scoring System gives it 99%, the 99th percentile of every CVE it scores.

How do I fix CVE-2015-3306?

Apply the vendor's fix or mitigation; CISA lists only vulnerabilities seen exploited. If you cannot patch now, restrict network access to the affected product. Check for signs of compromise since the date it was added to the list.

Sources: CISA Known Exploited Vulnerabilities catalogue (released 10 November 2026) and FIRST EPSS. Page compiled automatically by SAK T.L.M, the threat-intelligence tool of SAK T.E.C, on 13 November 2026.