What is CVE-2018-6332?

CVE-2018-6332 is a medium-severity vulnerability in Facebook Hhvm, classified under Uncontrolled Resource Consumption. CVSS score: 5.9/10. Published 2018-12-03.

How severe is CVE-2018-6332?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Resource exhaustion in Facebook Hhvm

CVE-2018-6332

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.

Vulnerability class: DoS (Denial of Service)

Published 2018-12-03 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.011 (63.9th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 64th percentile — 63.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Facebook Hhvm — versions 3.22.0, unspecified, 3.24.4

Weakness classification (CWE)

References

hhvm.com/blog/2018/03/15/hhvm-3.25.html (Vendor Advisory)

Frequently asked questions

What is CVE-2018-6332?: CVE-2018-6332 is a medium-severity vulnerability in Facebook Hhvm, classified under Uncontrolled Resource Consumption. CVSS score: 5.9/10. Published 2018-12-03.
How severe is CVE-2018-6332?: Medium severity. CVSS v3 base score is 5.9 out of 10.