node-tar,a Tar for Node.js, has a race condition vulnerability in versions up to and including 7.5.3. This is due to an incomplete handling of Unicode path collisions in the "path-reservations" system. On case-insensitive or normalization-insensitive filesystems (such as macOS APFS, In which it has been tested), the library fails to lock colliding paths (e.g., "ß" and "ss"), allowing them to be processed in parallel. This bypasses the library's internal concurrency safeguards and permits Symlink Poisoning attacks via race conditions. The library uses a "PathReservations" system to ensure that metadata checks and file operations for the same path are serialized. This prevents race conditions where one entry might clobber another concurrently. This is a Race Condition which enables Arbitrary File Overwrite. This vulnerability affects users and systems using node-tar on macOS (APFS/HFS+). Because of using "NFD" Unicode normalization (in which "ß" and "ss" are different), conflicting paths do not have their order properly preserved under filesystems that ignore Unicode normalization (e.g., APFS (in which "ß" causes an inode collision with "ss")). This enables an attacker to circumvent internal parallelization locks ("PathReservations") using conflicting filenames within a malicious tar archive. The patch in version 7.5.4 updates "path-reservations.js" to use a normalization form that matches the target filesystem's behavior (e.g., "NFKD"), followed by first "toLocaleLowerCase('en')" and then "toLocaleUpperCase('en')". As a workaround, users who cannot upgrade promptly, and who are programmatically using "node-tar" to extract arbitrary tarball data should filter out all "SymbolicLink" entries (as npm does) to defend against arbitrary file writes via this file system entry name collision issue.