Use After Free in Qt
CVE-2025-5991
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.
Vulnerability class: Use-After-Free
EPSS: 0.001 (2.1th percentile) — read the EPSS interpretation.
Affected products
- Qt — versions 0, 6.9.0, 6.9.1
- The Qt Company — versions 0, 6.9.0, 6.9.1