CVE-2019-11936: Facebook Hhvm

Critical severity, CVSS 9.8. EPSS: 1.5% chance of exploitation in the next 30 days.

Various APC functions accept keys containing null bytes as input, leading to premature truncation of input. This issue affects HHVM versions prior to 3.30.12, all versions between 4.0.0 and 4.8.5, all versions between 4.9.0 and 4.23.1, as well as 4.24.0, 4.25.0, 4.26.0, 4.27.0, 4.28.0, and 4.28.1.

Affected products

• Facebook Hhvm: before 3.30.12 (fixed in 3.30.12); from 4.0.0, up to and including 4.8.5; from 4.9.0, up to and including 4.23.1; version 4.24.0 only; version 4.25.0 only; version 4.26.0 only; …

Published 2019-12-04. Last modified 2026-06-17.