Integer underflow in TightVNC Server cursor shape trimming leads to out-of-bounds read

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-107614
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 integer underflow in WinCursorShapeUtils::trimTransparent() in GlavSoft TightVNC Server for Windows before 2.8.88 allows a local authenticated user to crash the server, and potentially read out-of-bounds memory, by causing a cursor shape with a width or height of zero to be processed on the DXGI capture path. The loop bound width - 1 wraps to 0xFFFFFFFF, producing an access roughly 4 GB beyond the 64 KB cursor buffer; a monochrome cursor of height 1 also becomes 0 because getCursorHeight() halves the height in place.

Risk And Classification

Primary CVSS: v3.1 6.1 MEDIUM from 33c584b5-0579-4c06-b2a0-8d8329fcab9c

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

Problem Types: CWE-125 | CWE-191 | CWE-191 CWE-191 Integer Underflow (Wrap or Wraparound) | CWE-125 CWE-125 Out-of-bounds Read

VersionSourceTypeScoreSeverityVector
3.133c584b5-0579-4c06-b2a0-8d8329fcab9cSecondary6.1MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
3.1CNACVSS6.1MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA GlavSoft TightVNC affected 2.8.88 custom Windows

References

ReferenceSourceLinkTags
sourceforge.net/p/vnc-tight/bugs/1661 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.

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