Cyber Resilience

CVE-2026-3787

HighLPE

Published: 08 March 2026

Published
08 March 2026
Modified
10 March 2026
KEV Added
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Patch
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CVSS Score v4 7.3 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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0017 6.1th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-3787 is a high-severity Untrusted Search Path (CWE-426) vulnerability in Uvnc Ultravnc. Its CVSS base score is 7.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique DLL (T1574.001); ranked at the 6.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A08:2025 Software or Data Integrity Failures

EU & UK References

Vulnerability details

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…

more

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.

CWE(s)
CWE-426CWE-427

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1574.001 DLL Stealth
Adversaries may abuse dynamic-link library files (DLLs) in order to achieve persistence, escalate privileges, and evade defenses.
attack.mitre.org →
Why these techniques?

Uncontrolled search path in Windows service directly enables DLL Search Order Hijacking (T1038).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Affected Assets

uvnc
ultravnc
1.6.4.0

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References