VULNERABILITY INTELLIGENCE

CVE-2020-1900

CVSS score9.8 CRITICAL

EPSS probability1.38%

CISA KEVNot currently listed

Published2021-03-11

Last modified2026-06-17

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Description

When unserializing an object with dynamic properties HHVM needs to pre-reserve the full size of the dynamic property array before inserting anything into it. Otherwise the array might resize, invalidating previously stored references. This pre-reservation was not occurring in HHVM prior to v4.32.3, between versions 4.33.0 and 4.56.0, 4.57.0, 4.58.0, 4.58.1, 4.59.0, 4.60.0, 4.61.0, 4.62.0.

Weakness classification

CWE-416: Use After Free

Primary references

cve-assign@fb.com — Patch, Third Party Advisory
cve-assign@fb.com — Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108 — Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Vendor Advisory