---
cve: "CVE-2026-44988"
severity: "HIGH"
cvss: 8.8
epss: "24%"
vendor: "LibVNC"
kev: false
exploited: false
published: "2026-05-27 15:16:29"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-02T21:11:18+02:00"
---

# CVE-2026-44988

> 8.8 HIGH · 🧪 PoC

## Beschreibung

LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Erforderlich | good |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- 5b270544b85233668b98161323297d418a8f5fd1 (Commit)

## Referenzen

- <https://github.com/LibVNC/libvncserver/security/advisories/GHSA-jcc5-8wj4-7c58>
- <https://github.com/LibVNC/libvncserver/commit/5b270544b85233668b98161323297d418a8f5fd1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-44988) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_