CVE Tools
Sign in

CVE-2021-40524

Published: Sep 5, 2021Updated: Nov 4, 2025 Sources: CVE List NVDCWE-434
7.5HIGH
NVD MITRE
EPSS Score
4.3%
Top 10.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Nuclei · OpenVAS

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.)

No summary for this CVE yet.

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
Open in CVSS calculator →

Weaknesses

CWE-434

Affected Products

pureftpd
oss-projectaka pure-ftpd
pure-ftpdOn-prem
Communications / email-server-client
and 1 more affected products View all →

Exploitability

Official Patch Available
Is your org exposed to CVE-2021-40524?We'll check your whole external perimeter for exposure — free. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

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 →
News mentions
Could not load news mentions.

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2021-40524 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows