CVE-2021-41380

MEDIUM

RealVNC Viewer 6.21.406 - Denial of Service via Crafted RFB Protocol Data

Title source: llm
STIX 2.1

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

References (1)

Core 1
Core References
Exploit, Third Party Advisory x_refsource_misc
https://gist.github.com/totaam/a90f2bb40f5b693ccec0ae903d021b03

Scores

CVSS v3 6.5
EPSS 0.0093
EPSS Percentile 56.0%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Details

CWE
CWE-20
Status published
Products (1)
realvnc/vnc_viewer 6.21.406
Published Sep 17, 2021
Tracked Since Feb 18, 2026