Vulnerability · Published Jan 21, 2026 · Assigned by VulnCheck
CVE-2021-47865ProFTPD 1.3.7a - Remote Denial of Service
High 7.5
In plain English
A high-severity resource allocation without limits in ProFTPD from ProFTPD. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 51.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
ProFTPD 1.3.7a contains a denial of service vulnerability that allows attackers to overwhelm the server by creating multiple simultaneous FTP connections. Attackers can repeatedly establish connections using threading to exhaust server connection limits and block legitimate user access.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | proftpd-dfsg | no fix listed | UBUNTU-CVE-2021-47865 |
| Ubuntu:24.04:LTS | proftpd-dfsg | no fix listed | UBUNTU-CVE-2021-47865 |
| Ubuntu:25.10 | proftpd-dfsg | no fix listed | UBUNTU-CVE-2021-47865 |
| Ubuntu:26.04:LTS | proftpd-dfsg | no fix listed | UBUNTU-CVE-2021-47865 |
| Ubuntu:26.10 | proftpd-dfsg | no fix listed | UBUNTU-CVE-2021-47865 |
Affected products (as reported)
Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- ExploitDB-49697 exploit
- ProFTPD Official Website product
- ProFTPD GitHub Repository issue-tracking
- VulnCheck Advisory: ProFTPD 1.3.7a - Remote Denial of Service third-party-advisory