CVE-2020-37134

HIGH 7.5

UltraVNC Viewer 1.2.4.0 - 'VNCServer' Denial of Service

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

UltraVNC Viewer 1.2.4.0 contains a denial of service vulnerability that allows attackers to crash the application by manipulating VNC Server input. Attackers can generate a malformed 256-byte payload and paste it into the VNC Server connection dialog to trigger an application crash.

CWE	CWE-770
Vendor	ultravnc team
Product	ultravnc viewer
Published	Feb 5, 2026
Last Updated	Mar 5, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

UltraVNC Team / UltraVNC Viewer

1.2.4.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

exploit-db.com: https://www.exploit-db.com/exploits/48291 uvnc.com: https://www.uvnc.com/ vulncheck.com: https://www.vulncheck.com/advisories/ultravnc-viewer-vncserver-denial-of-service

Credits

chuyreds