CVE-2019-11935: Facebook Hhvm

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

Insufficient boundary checks when processing a string in mb_ereg_replace allows access to out-of-bounds memory. 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.