CVE-2026-4962Public exploit

Code execution via service DLL search order

Published Mar 27, 2026 · Updated Mar 27, 2026

Uncontrolled DLL search in UltraVNC Service 1.6.0 through 1.6.4.0 allows local users to execute code via a planted library. The service can load a fake cryptbase.dll from the UltraVNC application directory instead of restricting resolution to the trusted system directory. On a standard Windows installation, planting that file requires local Administrator rights or an explicit ACL granting write access, and the loaded code runs in the service context.

CVSS severity7.0
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled DLL search in UltraVNC Service 1.6.0 through 1.6.4.0 allows local users to execute code via a planted library. The service can load a fake cryptbase.dll from the UltraVNC application directory instead of restricting resolution to the trusted system directory. On a standard Windows installation, planting that file requires local Administrator rights or an explicit ACL granting write access, and the loaded code runs in the service context.

The record

CVE
CVE-2026-4962
Published
Mar 27, 2026
Updated
Mar 27, 2026
Vendor
UltraVNC Team
Product
UltraVNC
Classifications
CWE-426, CWE-427, T1574.002
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Mar 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.6.0
  2. Affected versionversion=1.6.1
  3. Affected versionversion=1.6.2
  4. Affected versionversion=1.6.3
  5. Affected versionversion=1.6.4.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

UltraVNC Team · UltraVNCversion=1.6.0; version=1.6.1; version=1.6.2; version=1.6.3; version=1.6.4.0

Published CVSS scores

7.0VulDBCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
6.0VulDBAV:L/AC:H/Au:S/C:C/I:C/A:C
6.4VulDBCVSS: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 describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-426Untrusted Search Path
CWE-427Uncontrolled Search Path Element
T1574.002DLL Side-Loading

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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