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VulnerabilityPublished Updated

CVE-2025-5991: Qt · Use After Free

Affects QtSource CVE Database V5

0

Not known to be exploited · CVSS 2.1 Low · fixed in 6.9.1 : update Qt when convenient.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 4.0 base score
2.1Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.9.1
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Jun 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Mavenorg.qtproject/qtpkg:maven/org.qtproject/qtOther threatsAffected
  • =6.9.0
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade affected Qt installations from version 6.9.0 to 6.9.1 or later, where this vulnerability has been fixed. No other mitigation is required as the issue is resolved in the official patch.

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.

References

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