Is CVE-2020-1900 actively exploited?

No active exploitation of CVE-2020-1900 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2020-1900 be exploited remotely?

Yes. CVE-2020-1900 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2020-1900?

CVE-2020-1900 has a CVSS score of 9.8 (CRITICAL).

HOME VULNERABILITIESCVE-2020-1900

CRITICAL

CVE-2020-1900

CWE-416Published: March 11, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2020-1900 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-416): Use-after-free vulnerabilities involve accessing memory after it has been freed, often enabling arbitrary code execution.