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.)
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 13 | pure-ftpd | 1.0.50-1 | — |
| Debian 12 | pure-ftpd | 1.0.50-1 | — |
| Debian 11 | pure-ftpd | 1.0.49-4.1+deb11u1 | DLA-4360-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | pure-ftpd | No fix yet | — |
| Ubuntu 25.10 | pure-ftpd | No fix yet | — |
| Ubuntu 24.04 LTS | pure-ftpd | No fix yet | — |
| Ubuntu 22.04 LTS | pure-ftpd | No fix yet | — |
| Ubuntu 20.04 LTS | pure-ftpd | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | pure-ftpd | No fix yet | — |
| Ubuntu 16.04 LTS | pure-ftpd | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | pure-ftpd | 1.0.50-1.1 | openSUSE-SU-2024:11773-1 |
Automated scanner template
A ready-made Nuclei template detects this vulnerability automatically. Vulnerabilities with public scanner templates are typically probed across the internet soon after the template appears — exposed systems should be patched first.
- Pure-FTPd 1.0.23 < 1.0.50 - Arbitrary File Upload network/cves/2021/CVE-2021-40524.yaml
Source: projectdiscovery/nuclei-templates (MIT) — updated daily. Only links are listed.
Advisories 2
- openSUSE-SU-2024:11773-1 pure-ftpd-1.0.50-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- DLA-4360-1 pure-ftpd - security update Debian Security (DSA / DLA) · Nov 3, 2025