Vulnerability CVE-2021-32708

Vulnerability Name:

CVE-2021-32708 (CCN-204409)

Assigned:

2021-06-23

Published:

2021-06-23

Updated:

2021-09-20

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.

CVSS v3 Severity:

8.1 High (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)
7.1 High (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C)

Exploitability Metrics:	Attack Vector (AV): Network Attack Complexity (AC): High Privileges Required (PR): None User Interaction (UI): None
Scope:	Scope (S): Unchanged
Impact Metrics:	Confidentiality (C): High Integrity (I): High Availibility (A): High

9.8 Critical (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
8.5 High (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C)

Exploitability Metrics:	Attack Vector (AV): Network Attack Complexity (AC): Low Privileges Required (PR): None User Interaction (UI): None
Scope:	Scope (S): Unchanged
Impact Metrics:	Confidentiality (C): High Integrity (I): High Availibility (A): High

CVSS v2 Severity:

9.3 High (CVSS v2 Vector: AV:N/AC:M/Au:N/C:C/I:C/A:C)

Exploitability Metrics:	Access Vector (AV): Network Access Complexity (AC): Medium Authentication (Au): None
Impact Metrics:	Confidentiality (C): Complete Integrity (I): Complete Availibility (A): Complete

10.0 High (CCN CVSS v2 Vector: AV:N/AC:L/Au:N/C:C/I:C/A:C)

Exploitability Metrics:	Access Vector (AV): Network Access Complexity (AC): Low Athentication (Au): None
Impact Metrics:	Confidentiality (C): Complete Integrity (I): Complete Availibility (A): Complete