Flysystem is an open source file storage library for PHP. Prior to 3.35.3, the default WhitespacePathNormalizer in src/WhitespacePathNormalizer.php used by Filesystem across adapters calls preg_match with the u modifier and treats both false and 0 as falsy. A path containing malformed UTF-8 causes PCRE to return false, so paths that also contain control characters bypass CorruptedPathDetected::forPath() in normalizePath().
Filesystem::write() can store such names and Filesystem::listContents() can return the raw ANSI escape sequences, allowing hidden or spoofed terminal file listings when an administrator displays them. This issue is fixed in version 3.35.3.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
Required
User action required
Impact Assessment
Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products
thephpleague:flysystem
References 3
https://github.com/thephpleague/flysystem/security/advisories/GHSA-cxf4-7mrp-vv…
https://github.com/thephpleague/flysystem/security/advisories/GHSA-cxf4-7mrp-vvpr
https://github.com/thephpleague/flysystem/commit/ef4a9a557d769b5d472c4031257167…
https://github.com/thephpleague/flysystem/commit/ef4a9a557d769b5d472c403125716706a0d9cc77
https://github.com/thephpleague/flysystem/releases/tag/3.35.3
https://github.com/thephpleague/flysystem/releases/tag/3.35.3