CVE-2018-6332: Facebook Hhvm

Medium severity, CVSS 5.9. EPSS: 1.1% chance of exploitation in the next 30 days.

A potential denial-of-service issue in the Proxygen handling of invalid HTTP2 settings which can cause the server to spend disproportionate resources. This affects all supported versions of HHVM (3.24.3 and 3.21.7 and below) when using the proxygen server to handle HTTP2 requests.

Affected products

• Facebook Hhvm: up to and including 3.21.7; version 3.24.3 only

Published 2018-12-03. Last modified 2026-06-17.