# CVE-2026-105946: Qt Network QAuthenticator NTLM out-of-bounds read

Source: https://junglewise.ai/threats/cve-2026-105946-out-of-bounds-read-in-the-qauthenticator-ntlm-authentication  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-105946 · Severity: info · Published 2026-10-27

Qt Network, used by desktop and embedded applications for network communication, contains a flaw in NTLM authentication handling. When an application connects to a server or proxy and authenticates using NTLM, a malicious server can send a crafted challenge that triggers an out-of-bounds memory read, potentially exposing sensitive data from heap memory or crashing the application.

Technologies: [Qt Group Qt](https://junglewise.ai/threats/technologies/qt-group-qt). Vendors: [Qt Group](https://junglewise.ai/threats/vendors/qt-group).

## Quick answers

**Is CVE-2026-105946 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-105946 being exploited in the wild.

**How severe is CVE-2026-105946?** Informational severity, published 27 October 2026.

**Which products and versions are affected?** Qt Group Qt <UNKNOWN>.

**Is there a fix for CVE-2026-105946?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-105946 attacked?** It is attacked over the network or from the adjacent network, in a software library.

**Am I affected by CVE-2026-105946?** Check whether you run Qt Group Qt at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The QAuthenticator component in Qt Network fails to properly validate NTLM challenge messages, leading to an out-of-bounds read in memory when processing the response. The vulnerability affects applications using QNetworkAccessManager or QTcpSocket for NTLM authentication. An attacker controlling or intercepting a server or proxy can exploit this by sending a malicious NTLM challenge to leak heap memory or cause denial of service.

## Affected products

- Qt Group Qt <UNKNOWN>

## Timeline

- 2026-10-27: disclosed

## References

- [https://codereview.qt-project.org/c/qt/qtbase/+/744448](https://codereview.qt-project.org/c/qt/qtbase/+/744448)
- [https://codereview.qt-project.org/c/qt/qtbase/+/745457](https://codereview.qt-project.org/c/qt/qtbase/+/745457)

## Related threats

- [Qt null pointer dereference in QNetworkAccessManager HTTP/2](https://junglewise.ai/threats/cve-2026-96432-a-malicious-or-compromised-http-2-server-withholding-settings-ack)
- [Qt stack exhaustion in QXmlStreamReader::readElementText](https://junglewise.ai/threats/cve-2026-78253-uncontrolled-recursion-in-qxmlstreamreader-readelementtext-in-qt)