What’s Vulnerable › Vulnerabilities

CVE-2020-37134: UltraVNC Viewer 1.2.4.0 - 'VNCServer' Denial of Service

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-02-05 · updated 2026-06-17
• Weakness: CWE-770

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.

Affected products

• Uvnc UltraVNC Viewer: 1.2.4.0

References

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

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