A race condition in the one-pass compression functions of Zstandard prior to version 1.3.8 could allow an attacker to write bytes out of bounds if an output buffer smaller than the recommended size was used.

A vulnerability was found in zstd v1.4.10 where an attacker can supply empty string as an argument to the command line tool to cause buffer overrun.

In the Zstandard command-line utility prior to v1.4.1, output files were created with default permissions. Correct file permissions (matching the input) would only be set at completion time. Output files could therefore be readable or writable to unintended parties.

Beginning in v1.4.1 and prior to v1.4.9 due to an incomplete fix for CVE-2021-24031 the Zstandard command-line utility created output files with default permissions and restricted those permissions immediately afterwards. Output files could therefore momentarily be readable or writable to unintended parties.