CVE-2026-3787

Severity CVSS v4.0:

HIGH

Type:

CWE-426 Untrusted Search Path

Publication date:

08/03/2026

Last modified:

09/03/2026

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.

Impact

Vector 4.0

CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P CVSS v4.0 Severity and Metrics:

Base Score: 7.30 HIGH
Vector: CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P

Attack Vector (AV): Local
Attack Complexity (AC): High
Attack Requirements (AT): None
Privileges Required (PR): Low
User Interaction (UI): None
Confidentiality (VC): High
Integrity (VI): High
Availability (VA): High
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None
Exploit Maturity (E): POC

Base Score 4.0

7.30

Severity 4.0

HIGH

Vector 3.x

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.00 HIGH
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector (AV): Local
Attack Complexity (AC): High
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x

7.00

Severity 3.x

HIGH

Vector 2.0

AV:L/AC:H/Au:S/C:C/I:C/A:C CVSS v2.0 Severity and Metrics:

Base Score: 6.00 MEDIUM
Vector: AV:L/AC:H/Au:S/C:C/I:C/A:C

Attack Vector (AV): Local
Attack Complexity (AC): High
Authentication (Au): Single
Confidentiality (C): Complete
Integrity (I): Complete
Availability (A): Complete

Base Score 2.0

6.00

Severity 2.0

MEDIUM

CVE-2026-3787

Description

Impact

References to Advisories, Solutions, and Tools