7.1

CVE-2019-25600: uvnc ultravnc viewer Out-of-bounds Write

CVSS: 7.1v4.0HighDeferred
Published 22-03-2026Last modified 24-03-2026
Open JSON

Vulnerability summary

CVE-2019-25600 is a high (CVSS 7.1) Out-of-bounds Write vulnerability in uvnc ultravnc viewer. EPSS estimates a 0.70% chance of exploitation in the next 30 days, higher than 52.4% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
39/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.1/10
010
High · v4.0 (CVE.org)
EPSS score
0.70%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1exploit-database

Timeline

  1. 22-03-2026
    PublishedVulnerability first disclosed.
  2. 24-03-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

0.70%

Chance of exploitation in the next 30 days

Percentile

52%

Versus all other CVEs

30-day change

+0.01 pp

From 0.69% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.70%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • exploit-databasedoswindowsUnverified

    UltraVNC Viewer 1.2.2.4 - 'VNC Server' Denial of Service (PoC)

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Uvnc1 product

1 vendor · 1 product

References

4 links