CVE-2025-5991

Use after free in QHttp2ProtocolHandler

State: Published
Severity: 2.1 Low
Published: Jun 11, 2025
Updated: Jul 29, 2026
Reserved: Jun 11, 2025

Description

There is a "Use After Free" vulnerability in Qt's QHttp2ProtocolHandler in the QtNetwork module. This only affects HTTP/2 handling, HTTP handling is not affected by this at all. This happens due to a race condition between how QHttp2Stream uploads the body of a POST request and the simultaneous handling of HTTP error responses.

This issue only affects Qt 6.9.0 and has been fixed for Qt 6.9.1.

Scores

CVSS	Score	Vector	Source
4.0	2.1 Low	CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L	TQtC

Weaknesses

CWE-416 Use After Free

Affected Products

Product	Versions
QtQt	before 6.9.0Not affected 6.9.0Affected 6.9.1Not affected

References

https://codereview.qt-project.org/c/qt/qtbase/+/643777

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