CVE-2021-40524

HIGH
Published Sep 5, 20214y ago · Modified Jun 17, 20261w ago
7.5 CVSS 3.1
High
Find Similar
Published Sep 5, 2021 4y ago
Last Modified Jun 17, 2026 1w ago

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 Details

Base Score
7.5
Exploitability
3.9
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

No active exploitation signals — not in CISA KEV and no EPSS score yet.

Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 1

CWE-434 Unrestricted Upload of File with Dangerous Type Resource Mgmt

Affected Products 1

VendorProductVersionRange
pureftpdpure-ftpd*≥1.0.23  –  <1.0.50

References 4

  • github.com https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4
    PatchThird Party Advisory
  • github.com https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50
    PatchThird Party Advisory
  • github.com https://github.com/jedisct1/pure-ftpd/pull/158
    ExploitThird Party Advisory
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/11/msg00003.html

Remediation

  • github.com https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4
    PatchThird Party Advisory
  • github.com https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50
    PatchThird Party Advisory