CVE-2025-6338

Possible denial of service with multiple incoming connections to a Schannel based server with a TLS backend

State: Published
Severity: 9.2 Critical
Published: Oct 16, 2025
Updated: Jul 29, 2026
Reserved: Jun 19, 2025

Description

There is an incomplete cleanup vulnerability in Qt Network's Schannel support on Windows which can lead to a Denial of Service over a long period.

This issue affects Qt from 5.15.0 through 6.8.3, from 6.9.0 before 6.9.2.

Scores

CVSS	Score	Vector	Source
4.0	9.2 Critical	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H	TQtC

Weaknesses

CWE-459 Incomplete Cleanup

Affected Products

Product	Versions
QtQt	before 5.15.0Not affected 5.15.0 through 6.8.3Affected 6.8.4 to before 6.9.0Not affected 6.9.0 to before 6.9.2Affected

References

https://codereview.qt-project.org/c/qt/qtbase/+/651495

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