Security researcher Jonathan Leitschuh reported that Netflix Hollow (a Netflix OSS project available here: https://github.com/Netflix/hollow) writes to a local temporary directory before validating the permissions on it.
An attacker with the ability to create directories and set permissions on the local filesystem could pre-create this directory and read or modify anything written there by the Hollow process.
Since the Files.exists(parent) is run before creating the directories, an attacker can pre-create these directories with wide permissions. Additionally, since an insecure source of randomness is used, the file names to be created can be deterministically calculated.
Further details are available from the original reporter.
Avoid running Hollow in configurations that share a filesystem with less-trusted processes. May be fixed in a future release.