CVE-2019-25600

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 v4.0

7.1 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1

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

EPSS

0.69% chance of exploitation in the next 30 days, 50th percentile

Published

2026-03-22

Updated

2026-03-24

Proof-of-concept exploits (1)

• https://www.exploit-db.com/exploits/46702

References

• CVE Record
• NVD entry

Related

• CVE-2019-25599
• CVE-2019-25601
• CVE-2019-25598
• CVE-2019-25602
• CVE-2019-25597
• CVE-2019-25603