What is CVE-2016-6872?

CVE-2016-6872 is a critical-severity vulnerability in Facebook Hhvm, classified under Integer Overflow or Wraparound. CVSS score: 9.8/10. Published 2017-02-17.

How severe is CVE-2016-6872?

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

Integer overflow in Facebook Hhvm

CVE-2016-6872

Integer overflow in StringUtil::implode in Facebook HHVM before 3.15.0 allows attackers to have unspecified impact via unknown vectors.

Vulnerability class: Integer Overflow

Published 2017-02-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.022 (82.0th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 82nd percentile — 82.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.022 · newest: 0.022 · change: 0.000

Affected products

Facebook Hhvm

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

References

www.openwall.com/lists/oss-security/2016/08/11/1 (mailing-list, Mailing List, Third Party Advisory)
github.com/facebook/hhvm/commit/2c9a8fcc73a151608634d3e712973d192027c271 (Patch)
www.openwall.com/lists/oss-security/2016/08/19/1 (mailing-list, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2016-6872?: CVE-2016-6872 is a critical-severity vulnerability in Facebook Hhvm, classified under Integer Overflow or Wraparound. CVSS score: 9.8/10. Published 2017-02-17.
How severe is CVE-2016-6872?: Critical severity. CVSS v3 base score is 9.8 out of 10.