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Vulnerabilities

Vulnerability · CVE-2025-5991

There is a "Use After Free" vulnerability in Qt's QHttp2ProtocolHandler in the QtNetwork module.

Published Jun 11, 2025 · catalog updated Jul 29, 2026 · Qt Qt

Check if you run it

No confirmed exploitation is on record for CVE-2025-5991. EPSS is 0.14%. Act only if a listed version of Qt Qt is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Low2.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.14%
Remediation
Vendor / distro source
Affected products
vendor Qt Qt 6.9.0

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Qt Qt 6.9.06.9.0

How to fix CVE-2025-5991

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-5991. EPSS is 0.14%. Act only if a listed version of Qt Qt is installed.

Which versions are affected?

Compare what you have installed with Qt Qt 6.9.0 6.9.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.14%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 11, 2025 · EUVD

    Detected

    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.

  2. Jul 29, 2026 · EUVD

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2025-5991

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-5991

    30-day exploitation probability 0.1%

    first.org
  • EUVDVulnerability recordEUVD-2025-18092

    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 t

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.