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Vulnerabilities

Vulnerability · CVE-2026-3787

A weakness has been identified in UltraVNC 1.6.4.0 on Windows.

Published Mar 8, 2026 · catalog updated Jun 17, 2026 · A weakness has been

Check if you run it

No confirmed exploitation is on record for CVE-2026-3787. EPSS is 0.18%. Act only if a listed version of A weakness has been is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A weakness has been).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.18%
Remediation
Advisory link
Affected products
cpe uvnc/ultravnc

A weakness has been identified in UltraVNC 1.6.4.0 on Windows. This affects an unknown function in the library cryptbase.dll of the component Windows Service. This manipulation causes uncontrolled search path. The attack requires local access. A high degree of complexity is needed for the attack. The exploitability is reported as difficult. The vendor was contacted early about this disclosure but did not respond in any way.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe uvnc/ultravnc1.6.4.0

How to fix CVE-2026-3787

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-3787. EPSS is 0.18%. Act only if a listed version of A weakness has been is installed.

Which versions are affected?

Compare what you have installed with 1.6.4.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-426: Untrusted Search Path; CWE-427: Uncontrolled Search Path Element. EPSS 0.18%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Windows security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 8, 2026 · NIST NVD

    Detected

    A weakness has been identified in UltraVNC 1.6.4.0 on Windows. This affects an unknown function in the library cryptbase.dll of the component Windows Service. This manipulation causes uncontrolled search path. The attack requires local access. A high degree of complexity is needed for the attack. The exploitability is reported as difficult. The vendor was contacted early about this disclosure but

  2. Jun 17, 2026 · NIST NVD

    Updated

    A weakness has been identified in UltraVNC 1.6.4.0 on Windows. This affects an unknown function in the library cryptbase.dll of the component Windows Service. This manipulation causes uncontrolled search path. The attack requires local access. A high degree of complexity is needed for the attack. The exploitability is reported as difficult. The vendor was contacted early about this disclosure but

Sources

  • CVE.orgVulnerability recordCVE-2026-3787

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-3787

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-2026-3787

    A weakness has been identified in UltraVNC 1.6.4.0 on Windows. This affects an unknown function in the library cryptbase.dll of the component Windows Service. This manipulation causes uncontrolled search path. The attack requires local access. A high degree of complexity is neede

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.