CVE-2019-25600 PUBLISHED

UltraVNC Viewer 1.2.2.4 Denial of Service via Buffer Overflow

Assigner: VulnCheck
Reserved: 22.03.2026 Published: 22.03.2026 Updated: 22.03.2026

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.

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS Score: 7.1

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	High	Availability	None
Privileges Required	None
User Interaction	Passive

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS Score: 6.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	Required	Availability Impact	High

CVSS 3.1

Product Status

Vendor	Uvnc
Product	UltraVNC Viewer
Versions	Version 1.2.2.4 is affected

CVE-2019-25600 PUBLISHED

UltraVNC Viewer 1.2.2.4 Denial of Service via Buffer Overflow

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Problem Types