CVE-2016-1000005: Facebook Hhvm

Critical severity, CVSS 9.8. EPSS: 1.4% chance of exploitation in the next 30 days.

mcrypt_get_block_size did not enforce that the provided "module" parameter was a string, leading to type confusion if other types of data were passed in. This issue affects HHVM versions prior to 3.9.5, all versions between 3.10.0 and 3.12.3 (inclusive), and all versions between 3.13.0 and 3.14.1 (inclusive).

Affected products

• Facebook Hhvm: before 3.9.5 (fixed in 3.9.5); from 3.10.0, up to and including 3.12.3; from 3.13.0, up to and including 3.14.1

Published 2020-02-19. Last modified 2026-06-17.