CVE-2026-3787: UltraVNC Windows Service cryptbase.dll uncontrolled search path

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-08 · updated 2026-06-17
Weakness: CWE-426

Description

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.

Affected products

Kaspersky Lab UltraVNC: 1.6.4.0

References

https://drive.google.com/file/d/14ixv_1i4D2VrZWyl4RKsvFcN1AMF_qNx/view
https://vuldb.com/?ctiid.349754
https://vuldb.com/?id.349754
https://vuldb.com/?submit.767257

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