CVE-2020-1921: Facebook Hhvm

High severity, CVSS 7.5. EPSS: 1.2% chance of exploitation in the next 30 days.

In the crypt function, we attempt to null terminate a buffer using the size of the input salt without validating that the offset is within the buffer. This issue affects HHVM versions prior to 4.56.3, all versions between 4.57.0 and 4.80.1, all versions between 4.81.0 and 4.93.1, and versions 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0.

Affected products

• Facebook Hhvm: before 4.56.3 (fixed in 4.56.3); from 4.57.0, before 4.80.2 (fixed in 4.80.2); from 4.81.0, before 4.93.2 (fixed in 4.93.2); version 4.94.0 only; version 4.95.0 only; version 4.96.0 only; …

Published 2021-03-10. Last modified 2026-06-17.