CVE-2021-47865 ProFTPD 1.3.7a - Remote Denial of Service
Attackers can cause denial of service in ProFTPD by exhausting connection limits through multiple simultaneous FTP connections.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-47865?
CVE-2021-47865 is a high-severity denial of service vulnerability in ProFTPD, published on 21 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-770
Which versions are affected by CVE-2021-47865?
How do I fix CVE-2021-47865?
No fix has been published for CVE-2021-47865 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-47865 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47865 exists.
Sources
Also known as GHSA-mf77-27mv-mhm4, UBUNTU-CVE-2021-47865.