CVE-2025-5991
Use after free in QHttp2ProtocolHandler
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.
INFO
Published Date :
June 11, 2025, 8:15 a.m.
Last Modified :
July 29, 2026, 10:16 a.m.
Remotely Exploit :
No
Source :
a59d8014-47c4-4630-ab43-e1b13cbe58e3
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | LOW | a59d8014-47c4-4630-ab43-e1b13cbe58e3 |
Solution
- Update Qt to version 6.9.1.
- Apply relevant patches for QtNetwork module.
- Review HTTP/2 handling in applications.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-5991.
| URL | Resource |
|---|---|
| https://codereview.qt-project.org/c/qt/qtbase/+/643777 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-5991 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-5991
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-5991 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-5991 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by a59d8014-47c4-4630-ab43-e1b13cbe58e3
Jul. 29, 2026
Action Type Old Value New Value Changed Affected [{'vendor': 'The Qt Company', 'product': 'Qt', 'versions': [{'status': 'unaffected', 'version': '0', 'lessThan': '6.9.0', 'versionType': 'python'}, {'status': 'affected', 'version': '6.9.0'}, {'status': 'unaffected', 'version': '6.9.1'}], 'defaultStatus': 'unaffected'}] [{'vendor': 'Qt', 'product': 'Qt', 'versions': [{'status': 'unaffected', 'version': '0', 'lessThan': '6.9.0', 'versionType': 'python'}, {'status': 'affected', 'version': '6.9.0'}, {'status': 'unaffected', 'version': '6.9.1'}], 'defaultStatus': 'unaffected'}] Changed 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. 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. -
CVE Modified by a59d8014-47c4-4630-ab43-e1b13cbe58e3
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'The Qt Company', 'product': 'Qt', 'versions': [{'status': 'unaffected', 'version': '0', 'lessThan': '6.9.0', 'versionType': 'python'}, {'status': 'affected', 'version': '6.9.0'}, {'status': 'unaffected', 'version': '6.9.1'}], 'defaultStatus': 'unaffected'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2025-5991', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2025-06-11T13:17:41.670069Z'} -
New CVE Received by a59d8014-47c4-4630-ab43-e1b13cbe58e3
Jun. 11, 2025
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:L/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-416 Added Reference https://codereview.qt-project.org/c/qt/qtbase/+/643777