CVE-2021-32708
Time-of-check Time-of-use (TOCTOU) Race Condition in league/flysystem
- Published
- Jun 24, 2021
- Updated
- Aug 3, 2024
- Assigning CNA
- GitHub_M
- Evidence observed
- Aug 8, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HLow · next 30 days
- Percentile
- 88.6%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
Flysystem is an open source file storage library for PHP. The whitespace normalisation using in 1.x and 2.x removes any unicode whitespace. Under certain specific conditions this could potentially allow a malicious user to execute code remotely. The conditions are: A user is allowed to supply the path or filename of an uploaded file, the supplied path or filename is not checked against unicode chars, the supplied pathname checked against an extension deny-list, not an allow-list, the supplied path or filename contains a unicode whitespace char in the extension, the uploaded file is stored in a directory that allows PHP code to be executed. Given these conditions are met a user can upload and execute arbitrary code on the system under attack. The unicode whitespace removal has been replaced with a rejection (exception). For 1.x users, upgrade to 1.1.4. For 2.x users, upgrade to 2.1.1.
Sources
1- CVE-2021-32708Exploit
Affected versions of this package are vulnerable to Race Condition. The whitespace normalisation using in 1.x and 2.x removes any unicode whitespace. Under certain specific conditions this could potentially allow a malicious user to execute code remotely.
Responsible use
Use vulnerability information only on systems you own or are authorized to test. Kitploit links to public research metadata and does not store exploit code or malicious payloads.