---
id: CVE-2026-107611
title: >-
  An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC
  Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server
  to read heap memory beyond the palette allocation and crash the viewer by
  sending …
summary: >-
  An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC
  Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server
  to read heap memory beyond the palette allocation and crash the viewer by
  sending …
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H'
cwe:
  - CWE-125
vendor: GlavSoft
product: TightVNC
affected:
  - TightVNC < 2.8.88
published: '2026-10-08'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T15:17:45.440'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-107611'
references:
  - url: 'https://sourceforge.net/p/vnc-tight/bugs/1657/'
    label: 33c584b5-0579-4c06-b2a0-8d8329fcab9c
  - url: 'https://www.tightvnc.com/whatsnew.php'
    label: 33c584b5-0579-4c06-b2a0-8d8329fcab9c
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-08T14:02:42.563819Z'
ingestedAt: '2026-10-08T14:47:16.340Z'
---

## Overview

An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server to read heap memory beyond the palette allocation and crash the viewer by sending ZRLE-encoded tiles whose palette indices exceed the declared palette size. readPaletteRleTile() and readPackedPaletteTile() use the attacker-supplied index to look up colours without validating it against the palette size; out-of-bounds heap data is copied into the framebuffer (garbled display) or the read faults, terminating the viewer.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.