How severe is CVE-2026-3787?

CVE-2026-3787 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-3787 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-3787?

CVE-2026-3787 affects Uvnc Ultravnc. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-3787?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-3787 have an EU (EUVD) identifier?

Yes. CVE-2026-3787 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10277.

When was CVE-2026-3787 published?

CVE-2026-3787 was published on 2026-03-08 and last updated on 2026-06-17.

CVE-2026-3787

CVE-2026-3787 is a high-severity vulnerability in Uvnc Ultravnc with a CVSS 3.x base score of 7.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-426.

Key facts

Severity: High (CVSS 3.x base score 7.0)
CVSS v2: 6.0
CVSS v4: 6.4
EPSS exploit prediction: 0% (6th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-10277
Weakness: CWE-426
Affected product: Uvnc Ultravnc
Published: 2026-03-08
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-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 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.
How severe is CVE-2026-3787?: CVE-2026-3787 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-3787 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-3787?: CVE-2026-3787 affects Uvnc Ultravnc. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-3787?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-3787 have an EU (EUVD) identifier?: Yes. CVE-2026-3787 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10277.
When was CVE-2026-3787 published?: CVE-2026-3787 was published on 2026-03-08 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:uvnc:ultravnc:1.6.4.0:*:*:*:*:*:*:*

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