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CVE-2021-40524

Published: Sep 5, 2021Updated: Nov 4, 2025 Sources: CVE List NVDCWE-434
NVD MITRE
7.5CVSSHIGH
EPSS Score
4.4%
Top 10.0%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Am I actually vulnerable?1 Nuclei template available — see how to check your systems. How to verify

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 Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-434

Affected Products

pure-ftpdpureftpd
On-prem
Communications / email-server-client
n/an/a
pureftpdoss-projectCommunicationsaka pure-ftpd, pureftpd

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

3 techniques
Command and Control
Initial Access
Persistence
View detailed technique mapping

References

https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4
github.com
https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50
github.com
https://github.com/jedisct1/pure-ftpd/pull/158
github.com
and 1 more references View all →

Timeline

Published
Sep 5, 2021
Last Updated
Nov 4, 2025

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