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Vulnerability record · CVE-2021-47865 · published 21 January 2026

CVE-2021-47865: Allocation without limits vulnerability

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.

8.7 CVSS 4.0 High EPSS 0.61% · top 53.1% CWE-770 · Allocation without limits Deferred
8.7CVSS 4.0 base score
0.61%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
http://www.proftpd.org/
https://github.com/proftpd/proftpd/issues/1298
https://www.exploit-db.com/exploits/49697
https://www.vulncheck.com/advisories/proftpd-a-remote-denial-of-service

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-47865), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.