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.
Published 2021-06-24 17:15:08
Updated 2021-09-20 18:50:33
Source GitHub, Inc.
View at NVD,   CVE.org
Vulnerability category: Execute code

Exploit prediction scoring system (EPSS) score for CVE-2021-32708

0.71%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 80 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2021-32708

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
9.3
HIGH AV:N/AC:M/Au:N/C:C/I:C/A:C
8.6
10.0
NIST
8.1
HIGH CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
2.2
5.9
NIST
9.8
CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.9
5.9
GitHub, Inc.

CWE ids for CVE-2021-32708

  • The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state.
    Assigned by:
    • nvd@nist.gov (Primary)
    • security-advisories@github.com (Secondary)

References for CVE-2021-32708

Products affected by CVE-2021-32708

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