Is CVE-2021-41380 actively exploited?

No active exploitation of CVE-2021-41380 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-41380 be exploited remotely?

Yes. CVE-2021-41380 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-41380?

CVE-2021-41380 has a CVSS score of 6.5 (MEDIUM).

HOME VULNERABILITIESCVE-2021-41380

MEDIUM

CVE-2021-41380

CWE-20Published: September 17, 2021· Updated: Jun 17, 2026

6.5

CVSS v3.1

Official Description

RealVNC Viewer 6.21.406 allows remote VNC servers to cause a denial of service (application crash) via crafted RFB protocol data. NOTE: It is asserted that this issue requires social engineering a user into connecting to a fake VNC Server. The VNC Viewer application they are using will then hang, until terminated, but no memory leak occurs - the resources are freed once the hung process is terminated and the resource usage is constant during the hang. Only the process that is connected to the fake Server is affected. This is an application bug, not a security issue

NVD Source

Technical Analysis

CVE-2021-41380 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.