CVE-2021-24031: Facebook Zstandard

Medium severity, CVSS 5.5. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Facebook Zstandard: before 1.4.1 (fixed in 1.4.1)

Published 2021-03-04. Last modified 2026-06-17.