High 7.5Published Feb 5, 2026

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

Updated under an hour ago (Oct 27, 2026, 4:10 AM ET)

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It affects UltraVNC Team UltraVNC Viewer. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Deferred
Record last updated: Mar 4, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

UltraVNC Team UltraVNC Viewer ultravnc_team:ultravnc_viewer (from the name)	1.2.4.0	CNA record

References

References

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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.