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Qt Network CVE-2026-76151

| EUVDEUVD-2026-80385 MEDIUM
Out-of-bounds Read (CWE-125)
2026-09-16 Qt GHSA-32mm-x94q-6h38
4.6
CVSS 4.0 · Vendor: Qt
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Severity by source

Vendor (Qt) PRIMARY
4.6 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/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:N/R:A/V:X/RE:X/U:X
vuln.today AI
5.9 MEDIUM

Network-reachable but requires the client to contact a malicious/compromised server (AC:H), no auth (PR:N); impact is crash-only, so C:N/I:N/A:H.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (Qt).

CVSS VectorVendor: Qt

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

4
Metadata Corrected
Sep 16, 2026 - 10:40 vuln.today
tag: Information Disclosure removed
Metadata Corrected
Sep 16, 2026 - 10:40 vuln.today
tag: RCE removed
Analysis Generated
Sep 16, 2026 - 10:36 vuln.today
CVE Published
Sep 16, 2026 - 09:58 cve.org
MEDIUM 4.6

DescriptionCVE.org

Out-of-bounds read (buffer over-read) in the HTTP Cache-Control response header parsing in the QtNetwork module in Qt Group Qt 6.0.0 through 6.8.8, and 6.9.0 through 6.11.1, allows remote attackers to cause a denial of service (application crash) via an excessively large Cache-Control header value returned by an untrusted or compromised HTTP server to an application using QNetworkAccessManager. Only the client side of the connection is affected and 32-bit builds are not affected; the out-of-bounds access is read-only, with no information disclosure and no code execution.

AnalysisAI

An out-of-bounds read in the HTTP Cache-Control response header parser of the QtNetwork module lets a hostile or compromised HTTP server crash 64-bit client applications built on Qt 6.0.0-6.8.8 or 6.9.0-6.11.1 that use QNetworkAccessManager. The trigger is an excessively large Cache-Control header value returned to the requesting client; because the over-read is read-only, the outcome is limited to a denial of service (application crash) with no information disclosure and no code execution, and only the client side of the connection is affected - 32-bit builds are not affected. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
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Exploit
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Execution
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Impact
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Vulnerability AssessmentAI

Exploitation The victim must run a 64-bit build of a Qt application (Qt 6.0.0-6.8.8 or 6.9.0-6.11.1) that uses QNetworkAccessManager to make HTTP requests, and that application must connect to an untrusted, attacker-controlled, or compromised HTTP server which returns an excessively large Cache-Control response header. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a low-to-moderate real-world risk despite the alarmist tags. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Primary remediation is to apply the upstream Qt fix referenced at https://codereview.qt-project.org/c/qt/qtbase/+/752129; because this reference is a Gerrit/commit-level change rather than a tagged release, upstream fix availability is confirmed but a released patched version has not been independently confirmed, so integrators should track the Qt 6.x release notes for the first tag containing this change and rebuild/redeploy affected applications against it (64-bit builds are the priority, since 32-bit builds are unaffected). … Detailed patch versions, workarounds, and compensating controls in full report.

Threat intelligence, references, and detailed analysis are available after sign-in.

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CVE-2026-76151 vulnerability details – vuln.today

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