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CVE-2021-41380

RealVNC Viewer 6.21.406 allows remote VNC servers to cause a denial of service (application crash) via crafted RFB protocol data. NOTE: It…

Medium6.5EPSS 0.96%
Published
Updated
Reserved
Assigned by
mitre

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

Scores

CVSS scores of CVE-2021-41380, by who scored it
Scored byCVSSScoreVector
NVDNVD · Modified3.1Medium6.5CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.96% · top 38% of all CVEs (6 Nov 2026)
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The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.

Weakness

Affected products

  • n/a

    • affected n/a

References (1)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .