7.5

CVE-2020-37134: ultravnc team ultravnc viewer

CVSS: 7.5v3.1HighDeferred
Published 05-02-2026Last modified 05-03-2026
Open JSON

Vulnerability summary

CVE-2020-37134 is a high (CVSS 7.5) vulnerability in ultravnc team ultravnc viewer. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 34% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
40/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.41%
0%100%
Low · +0.04 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1exploit-database

Timeline

  1. 05-02-2026
    PublishedVulnerability first disclosed.
  2. 05-03-2026
    Last modifiedVulnerability information updated.

Description

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 metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

0.41%

Chance of exploitation in the next 30 days

Percentile

34%

Versus all other CVEs

30-day change

+0.04 pp

From 0.38% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.41%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • exploit-databasedoswindowsUnverified

    UltraVNC Viewer 1.2.4.0 - 'VNCServer' Denial of Service (PoC)

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Ultravnc team1 product

1 vendor · 1 product

References

3 links