High severity · published Sep 5, 2021
CVE-2021-40524
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…
7.5
CVSS
4.3%
EPSS
No
On KEV
Description
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.)
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)4.3% · higher than 91% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PU
Pure-ftpd · Pureftpd
1.0.23 before 1.0.50 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-40524
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-40524
Patch
https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4
Patch
https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50
Exploit
https://github.com/jedisct1/pure-ftpd/pull/158
lists.debian.org
https://lists.debian.org/debian-lts-announce/2025/11/msg00003.html
More from Pure-ftpd
9.8
CVE-2017-12170
Downstream 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 after update and service…
8.6
CVE-2024-48208
pure-ftpd before 1.0.52 is vulnerable to Buffer Overflow
7.5
CVE-2020-35359
Pure-FTPd 1.0.48 allows remote attackers to prevent legitimate server use by making enough connections to exceed the connection limit
7.5
CVE-2020-9274
An issue was discovered in Pure-FTPd 1.0.49
7.5
CVE-2020-9365
An issue was discovered in Pure-FTPd 1.0.49