Vulnerability record · CVE-2021-40524 · published 5 September 2021

CVE-2021-40524: Pureftpd pure-ftpd unrestricted file upload vulnerability

Pureftpd · Pure Ftpd

In Pure-FTPd before 1.0.50, an incorrect max_filesize quota mechanism in the server allows attackers to upload files of unbounded size, which may lead to denial of service or a server hang. This occurs because a certain greater-than-zero test does not anticipate an initial -1 value. (Versions 1.0.23 through 1.0.49 are affected.)

7.5 CVSS 3.1 High EPSS 4.3% · top 9.2% CWE-434 · Unrestricted file upload

7.5CVSS 3.1 base score, v2 5.0

4.3%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

7References, 2 tagged exploit

17 Jun 2026Last modified by NVD

Description

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Pure Ftpd Pureftpd

References

Link	Tags
https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4	PatchThird Party Advisory
https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50	PatchThird Party Advisory
https://github.com/jedisct1/pure-ftpd/pull/158	ExploitThird Party Advisory
https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4	PatchThird Party Advisory
https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50	PatchThird Party Advisory
https://github.com/jedisct1/pure-ftpd/pull/158	ExploitThird Party Advisory
https://lists.debian.org/debian-lts-announce/2025/11/msg00003.html

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Related vulnerabilities

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

9.8CVE-2017-12170Pureftpd pure-ftpd vulnerabilityDownstream version 1.0.46-1 of pure-ftpd as shipped in Fedora was vulnerable to packaging error due to which the original configuration was ignored a…EPSS 1.5%21 Sep 2017 8.6CVE-2024-48208Pureftpd pure-ftpd out-of-bounds read vulnerabilitypure-ftpd before 1.0.52 is vulnerable to Buffer Overflow. There is an out of bounds read in the domlsd() function of the ls.c file.EPSS 1.6%24 Oct 2024 7.5CVE-2020-35359Pureftpd pure-ftpd allocation without limits vulnerabilityPure-FTPd 1.0.48 allows remote attackers to prevent legitimate server use by making enough connections to exceed the connection limit.EPSS 4.5%26 Dec 2020 7.5CVE-2020-9274Pureftpd pure-ftpd vulnerabilityAn issue was discovered in Pure-FTPd 1.0.49. An uninitialized pointer vulnerability has been detected in the diraliases linked list. When the *lookup…EPSS 6.0%26 Feb 2020 7.5CVE-2020-9365Pureftpd pure-ftpd out-of-bounds read vulnerabilityAn issue was discovered in Pure-FTPd 1.0.49. An out-of-bounds (OOB) read has been detected in the pure_strcmp function in utils.c.EPSS 7.1%24 Feb 2020 7.5CVE-2019-20176Pureftpd pure-ftpd uncontrolled resource consumption vulnerabilityIn Pure-FTPd 1.0.49, a stack exhaustion issue was discovered in the listdir function in ls.c.EPSS 4.4%31 Dec 2019 5.8CVE-2011-1575Pureftpd pure-ftpd vulnerabilityThe STARTTLS implementation in ftp_parser.c in Pure-FTPd before 1.0.30 does not properly restrict I/O buffering, which allows man-in-the-middle attac…EPSS 33%23 May 2011 4.4CVE-2011-0988Pureftpd pure-ftpd permissions and access controls vulnerabilitypure-ftpd 1.0.22, as used in SUSE Linux Enterprise Server 10 SP3 and SP4, and Enterprise Desktop 10 SP3 and SP4, when running OES Netware extensions,…EPSS 0.34%18 Apr 2011

Source: NIST National Vulnerability Database (record CVE-2021-40524), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.