DLL search order hijacking via screenhooks libraries in TightVNC Server

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-107615
StatePUBLISHED
Assignersecurin
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-08 14:16:50 UTC
Updated2026-10-08 15:17:45 UTC
DescriptionAn uncontrolled search path element vulnerability in GlavSoft TightVNC Server for Windows before 2.8.88 allows a local authenticated user to execute arbitrary code with SYSTEM privileges. DynamicLibrary::init() (and ThemeLib) load screenhooks32.dll / screenhooks64.dll with LoadLibrary() using a bare file name and no LOAD_LIBRARY_SEARCH_* flags, so the TightVNC service follows the default DLL search order and loads an attacker-planted DLL from a writable directory earlier in that order (for example, an installation directory with permissive ACLs).

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 33c584b5-0579-4c06-b2a0-8d8329fcab9c

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-427 | CWE-427 CWE-427 Uncontrolled Search Path Element

VersionSourceTypeScoreSeverityVector
3.133c584b5-0579-4c06-b2a0-8d8329fcab9cSecondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA GlavSoft TightVNC affected 2.8.88 custom Windows

References

ReferenceSourceLinkTags
sourceforge.net/p/vnc-tight/bugs/1666 33c584b5-0579-4c06-b2a0-8d8329fcab9c sourceforge.net
www.tightvnc.com/whatsnew.php 33c584b5-0579-4c06-b2a0-8d8329fcab9c www.tightvnc.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Arjun Basnet from Securin (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-05-30T00:00:00.000ZReported to GlavSoft
CNA2026-06-02T00:00:00.000ZVendor acknowledged
CNA2026-06-19T00:00:00.000ZTightVNC 2.8.88 released with fix

Solutions

CNA: Upgrade TightVNC for Windows to version 2.8.88 or later.

Workarounds

CNA: Ensure the TightVNC installation directory and every directory on the system PATH are writable only by administrators.

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report