CVE-2026-107614

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

Published Oct 8, 2026 CVSS 3.1 · 6.1 Medium EPSS < 1% KEV · Not listed
Description
An 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.

Remediation

Vendor Solution

Upgrade TightVNC for Windows to version 2.8.88 or later.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Glavsoft
Glavsoft tightvnc
Vendors & Products Glavsoft
Glavsoft tightvnc
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description An 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.
Title Integer underflow in TightVNC Server cursor shape trimming leads to out-of-bounds read
Weaknesses CWE-125
CWE-191
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
securin
Published
Updated
Oct 8, 2026, 2:01 PM
Reserved
Oct 8, 2026, 1:23 PM
Status
Awaiting Analysis
Published
Oct 8, 2026, 2:16 PM
Modified
Oct 8, 2026, 9:10 PM