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Exploited vulnerability · CISA KEV

Is CVE-2015-3306 exploited? Yes: in CISA KEV since 8 Oct 2026

Gociux · ProFTPD · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2015-3306, ProFTPD Improper Access Control Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 8 Oct 2026, 4161 days after it was published. It affects ProFTPD. If you run it, CISA's required action is: 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.

exploitedYesCISA KEV · 8 Oct 2026
ransomwareNot knownno confirmed use
EPSStop 1%among the most likely CVEs to be exploited
severity10CVSS 3.1 · critical
US federal due11 Oct 2026BOD 22-01 deadline

What it is

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.

VendorProFTPD (1 exploited CVE in KEV)
ProductProFTPD
VulnerabilityProFTPD Improper Access Control Vulnerability
WeaknessCWE-284
Published18 May 2015
Added to KEV8 Oct 2026
Reported by (CNA)mitre

What to do

  1. Check whether you run it. Look for ProFTPD in your asset inventory, including appliances and cloud images. Stack check lists every exploited ProFTPD CVE at once.
  2. Apply the fix. 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.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 18 May 2015.
  4. Get told next time. Email alerts when CISA adds a CVE for ProFTPD.

References

Questions

Is CVE-2015-3306 being exploited?

Yes. CISA added CVE-2015-3306 to the Known Exploited Vulnerabilities catalog on 8 Oct 2026, which means there is reliable evidence of exploitation in the wild.

Is CVE-2015-3306 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2015-3306?

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. Check ProFTPD's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected ProFTPD and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in October 2026 · act-now radar.

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