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Vulnerability · Published Oct 8, 2026 · Assigned by securin

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

Medium 6.1

In plain English

A medium-severity out-of-bounds read in TightVNC from GlavSoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 1% of all known vulnerabilities).

Severity (CVSS 3.1)6.1Medium
Exploit odds (30 days)0.1%top 98.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Ubuntu:22.04:LTStightvncno fix listedUBUNTU-CVE-2026-107614
Ubuntu:24.04:LTStightvncno fix listedUBUNTU-CVE-2026-107614
Ubuntu:26.04:LTStightvncno fix listedUBUNTU-CVE-2026-107614

Affected products (as reported)

VendorProductVersions
GlavSoft TightVNC 0 – before 2.8.88

Weakness: CWE-191, CWE-125 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H

References