---
id: "CVE-2026-105946"
kind: "vulnerability"
aliases: ["CVE-2026-105946"]
title: "Qt: NTLM challenge parsing reads out of bounds, leaking heap memory"
severity: "medium"
cvss: 5.3
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["desktop-apps", "ntlm", "qt", "runtime"]
not_affected_if: ["no-ntlm-auth", "trusted-servers-only"]
published_at: "2026-10-27T07:16:31+00:00"
first_seen_at: "2026-10-27T07:30:44+00:00"
updated_at: "2026-10-27T07:31:57+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-105946", "first_seen_at": "2026-10-27T07:30:44+00:00"}]
---

# Qt: NTLM challenge parsing reads out of bounds, leaking heap memory

A crafted NTLM challenge from a malicious server or proxy makes the Qt Network module read past a buffer during QAuthenticator handling. An attacker can read heap memory from the client application or crash it.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Qt version with `qmake --version` or the Qt SDK version in the build environment
- Search the code for `QNetworkAccessManager` or `QTcpSocket` used with NTLM authentication

## Timeline

- 2026-10-27T07:30:44+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-105946

## From the sources

Out-of-bounds read in the QAuthenticator NTLM authentication handling in the Qt Network module in Qt Group Qt allows remote attackers to obtain sensitive information (heap memory contents) or cause a denial of service (application crash) via a crafted NTLM challenge sent by a malicious server or proxy, when an application using QNetworkAccessManager or QTcpSocket authenticates with NTLM.

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