---
cve: "CVE-2026-9499"
severity: "MEDIUM"
cvss: 6.3
epss: "0.3%"
vendor: "Qt"
kev: false
exploited: false
published: "2026-07-21 14:16:35"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-10-01T12:07:40+02:00"
---

# CVE-2026-9499

> 6.3 MEDIUM

## Beschreibung

An out-of-bounds read (buffer over-read) vulnerability exists in QTextCodec::codecForName() in Qt. When the function is called with a QByteArray that is not NUL-terminated (for example, one created with QByteArray::fromRawData()), the codec-name matching routine reads past the end of the supplied buffer. In most cases this results in an incorrect text codec being selected; in the worst case, if the over-read reaches unmapped memory, the process crashes (denial of service). The over-read is bounded by the length of the longest codec-name candidate, and the out-of-bounds bytes are only compared internally against Qt's fixed list of codec names, so no data is disclosed to an attacker. Applications that do not pass non-NUL-terminated QByteArrays to QTextCodec::codecForName() are not exposed. The affected code resides in the Qt5Compat module from Qt 6.0.0 onward, and in Qt Core (qtbase) in Qt 4.x and Qt 5.x.

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **no**
  - Technical Impact: **partial**

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## BSI-Hinweise (deutsch)

- [QT: Schwachstelle ermöglicht Denial of Service](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-2459) — _BSI-Einstufung: mittel_
  Ein entfernter, anonymer Angreifer kann eine Schwachstelle in QT ausnutzen, um einen Denial of Service Angriff durchzuführen.

## Referenzen

- <https://codereview.qt-project.org/c/qt/qt5compat/+/723911>
- <https://codereview.qt-project.org/c/qt/qt5compat/+/724348>
- <https://codereview.qt-project.org/c/qt/qt5compat/+/724995>
- <https://codereview.qt-project.org/c/qt/tqtc-qt5compat/+/725112>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-9499) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_