Flysystem: WhitespacePathNormalizer's control-character (CorruptedPathDetected) check is bypassed by malformed UTF-8 in the path, affecting every adapter

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

• league/flysystem 3.35.3Fixed version · GitHub Advisories · composer package league/flysystem: upgrade to 3.35.3 or later (affected <= 3.35.2)

[ Packages ]Affected open-source packages

• league/flysystem composerAffected <= 3.35.2 · fixed in 3.35.3 · GHSA-cxf4-7mrp-vvpr

[ References ]References

• github.com/thephpleague/flysystem/commit/ef4a9a557d769b5d472c403125716706a0d9cc77
• github.com/thephpleague/flysystem/releases/tag/3.35.3
• github.com/thephpleague/flysystem/security/advisories/GHSA-cxf4-7mrp-vvpr