Arbitrary file upload in Pure-FTPd - CVE-2021-40524
Published: September 5, 2021 / Updated: June 21, 2025
Vulnerability identifier: #VU111717
CSH Severity: Medium
CVSS v4.0: 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:U/U:Green
CVE-ID: CVE-2021-40524
CWE-ID: CWE-434
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: PureFTPd.org
Affected software:
Pure-FTPd
Pure-FTPd
Detailed vulnerability description
The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.
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.)
How to mitigate CVE-2021-40524
Install update from vendor's website.