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 server hang.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (4.29%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 4.29% probability · 91th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-434
- Affected
- pureftpd/pure-ftpd
- Source
- cve@mitre.org
References
- https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4Patch, Third Party Advisory
- https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50Patch, Third Party Advisory
- https://github.com/jedisct1/pure-ftpd/pull/158Exploit, Third Party Advisory
- https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4Patch, Third Party Advisory
- https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50Patch, Third Party Advisory
- https://github.com/jedisct1/pure-ftpd/pull/158Exploit, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2025/11/msg00003.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.