CVE-2026-3787: uvnc ultravnc Untrusted Search Path
Vulnerability summary
CVE-2026-3787 is a high (CVSS 7.3) Untrusted Search Path vulnerability in uvnc ultravnc. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.4% of scored vulnerabilities.
Timeline
- 08-03-2026PublishedVulnerability first disclosed.
- 10-03-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
7 scores · 2 sources · 4 versions- NVDNIST6.4MediumCVSS: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:XDiffers
- NVDNIST7.0HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- NVDNIST6.0MediumAV:L/AC:H/Au:S/C:C/I:C/A:C
EPSS trend
Probability
0.18%
Chance of exploitation in the next 30 days
Percentile
7%
Versus all other CVEs
30-day change
+0.02 pp
From 0.17% on 20-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-426Untrusted Search PathThe product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product's direct control.
- CWE-427Uncontrolled Search Path ElementThe product uses a fixed or controlled search path to find resources, but one or more locations in that path can be under the control of unintended actors.
Affected systems
Uvnc1 product
- ultravnc1.6.4.0
1 vendor · 1 product