Denial of Service Vulnerability in ProFTPD by ProFTPD
CVE-2021-47865

8.7HIGH

Key Information:

Vendor

Proftpd

Status
Proftpd
Vendor
CVE Published:
21 January 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2021-47865?

ProFTPD version 1.3.7a is susceptible to a denial of service vulnerability that enables malicious actors to disrupt server functionality. By triggering multiple simultaneous FTP connections, attackers can exploit threading mechanisms, leading to an exhaustion of server connection limits, which in turn prevents legitimate users from accessing the server.

Affected Version(s)

ProFTPD 1.3.7a

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2021-47865 - Proof of Concept

References

https://www.exploit-db.com/exploits/49697
exploit
http://www.proftpd.org/
product
https://github.com/proftpd/proftpd
product

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

xynmaps
JSON
.