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.
This page covers CVE-2025-5991 as tracked by Ubuntu, for the package qt6-base. No fixed version has been recorded for this distribution yet.
This issue can be reached with local access to the system, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. Rated impact: confidentiality low, integrity low, availability low.
The score comes from this vector: 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
UBUNTU-CVE-2025-5991 is recorded against 2 packages.
Published on 11 June 2025 and last revised on 20 May 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
ubuntu.com (Report)
www.cve.org (Report)
codereview.qt-project.org (Report)
qt6-base has other advisories on record. If you are patching this one, these are worth checking on the same host:
Each distribution ships its own build and its own fixed version. Pick the one you run:
Details
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
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| qt6-base | — | — |
| qtbase-opensource-src-gles | — | — |
References
Similar Threats
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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.
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