CVE-2020-37134

UltraVNC Viewer 1.2.4.0 - 'VNCServer' Denial of Service

Published Feb 5, 2026 CVSS 4.0 · 4.6 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Ultravnc vnc Viewer
CPEs cpe:2.3:a:ultravnc:vnc_viewer:1.2.4.0:*:*:*:*:*:*:*
Vendors & Products Ultravnc vnc Viewer
Type Values Removed Values Added
First Time appeared Ultravnc
Ultravnc ultravnc
Vendors & Products Ultravnc
Ultravnc ultravnc
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title UltraVNC Viewer 1.2.4.0 - 'VNCServer' Denial of Service
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 4.6, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Mar 5, 2026, 1:28 AM
Reserved
Feb 3, 2026, 4:27 PM
Status
Deferred
Published
Feb 5, 2026, 5:16 PM
Modified
Jun 17, 2026, 3:17 AM