What’s Vulnerable › Vulnerabilities

CVE-2019-25600: UltraVNC Viewer 1.2.2.4 Denial of Service via Buffer Overflow

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-22 · updated 2026-06-17
• Weakness: CWE-787

Description

UltraVNC Viewer 1.2.2.4 contains a denial of service vulnerability that allows attackers to crash the application by supplying an oversized string to the VNC Server input field. Attackers can paste a malicious string containing 256 repeated characters into the VNC Server field and click Connect to trigger a buffer overflow that crashes the viewer.

Affected products

• Uvnc UltraVNC Viewer: 1.2.2.4

References

• https://www.exploit-db.com/exploits/46702
• https://www.uvnc.com/
• https://www.uvnc.com/downloads/ultravnc/126-download-ultravnc-1224.html
• https://www.vulncheck.com/advisories/ultravnc-viewer-denial-of-service-via-buffer-overflow

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