What is CVE-2016-1000004?

CVE-2016-1000004 is a critical-severity vulnerability in Facebook Hhvm, classified under Insufficient Verification of Data Authenticity. CVSS score: 9.8/10. Published 2020-02-19.

How severe is CVE-2016-1000004?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Facebook Hhvm

CVE-2016-1000004

Insufficient type checks were employed prior to casting input data in SimpleXMLElement_exportNode and simplexml_import_dom. 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).

Published 2020-02-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (51.6th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 51.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Facebook Hhvm

Weakness classification (CWE)

CWE-345 — Insufficient Verification of Data Authenticity

References

github.com/facebook/hhvm/commit/8e7266fef1f329b805b37f32c9ad0090215ab269 (Patch, Third Party Advisory)
www.facebook.com/security/advisories/cve-2016-1000004 (Third Party Advisory)

Frequently asked questions

What is CVE-2016-1000004?: CVE-2016-1000004 is a critical-severity vulnerability in Facebook Hhvm, classified under Insufficient Verification of Data Authenticity. CVSS score: 9.8/10. Published 2020-02-19.
How severe is CVE-2016-1000004?: Critical severity. CVSS v3 base score is 9.8 out of 10.