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CVE-2026-107614— Integer underflow in TightVNC Server cursor shape trimming leads to out-of-bounds read

Quick assessment

Affected
GlavSoft TightVNC
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 GlavSoft TightVNC Server for Windows 2.8.88 之前的版本中，WinCursorShapeUtils::trimTransparent() 函数存在整数下溢漏洞。本地经过身份验证的用户可以通过触发对宽度或高度为零的光标形状在 DXGI 捕获路径上的处理，导致服务器崩溃，并可能越界读取内存。具体而言，循环边界表达式 width - 1 会发生回绕，变为 0xFFFFFFFF，从而在 64 KB 的光标缓冲区之后约 4 GB 的位置进行内存访问；此外，对于高度为 1 的单色光

CVSS 6.1 · Medium

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 1

VendorProduct Version RangeStatus
GlavSoft TightVNC < 2.8.88 affected
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I. Basic Information for CVE-2026-107614

Vulnerability Information
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Vulnerability Title
Integer underflow in TightVNC Server cursor shape trimming leads to out-of-bounds read
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
GlavSoft TightVNC 0 ~ 2.8.88 -

II. Public POCs for CVE-2026-107614

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III. Intelligence Information for CVE-2026-107614

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Vendor Pages for CVE-2026-107614 (1)

Same Patch Batch · GlavSoft · 2026-10-08 · 5 CVEs total

CVE-2026-107612 7.8 HIGH World-accessible IPC shared memory with predictable name in TightVNC Server
CVE-2026-107615 7.8 HIGH DLL search order hijacking via screenhooks libraries in TightVNC Server
CVE-2026-107611 7.1 HIGH Out-of-bounds read in TightVNC Viewer ZRLE palette decoding
CVE-2026-107613 5.9 MEDIUM NULL pointer dereference in TightVNC Server Win8ScreenDriver after failed DXGI re-initiali

IV. Related Vulnerabilities

Same product: TightVNC
Same vendor: GlavSoft
Same weakness: CWE-191

V. Comments for CVE-2026-107614

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