CVE-2021-41380

MEDIUM 6.5CVE-2021-41380 · Published 17/09/2021 · updated 17/06/2026

In short

CVE-2021-41380 is a MEDIUM (CVSS 6.5) vulnerability affecting vnc viewer (realvnc).
Chance of exploitation in the next 30 days (EPSS): 0.96%, higher than 61.5% of all vulnerabilities.
No patched version is listed yet: follow the vendor's advisory in References.

Package	Affected versions	Patched versions
vnc viewer realvnc	`= 6.21.406`	No fix yet

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

gist.github.com/totaam/a90f2bb40f5b693ccec0ae903d021b03 · Exploit

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