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QtApplication

CVE-2024-39936

MEDIUM · 5.9 CVSS v3.1 Published 2024-07-04
Fix available
A fix is available. Upgrade to 5.15.18 / 6.2.13 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue was discovered in HTTP2 in Qt before 5.15.18, 6.x before 6.2.13, 6.3.x through 6.5.x before 6.5.7, and 6.6.x through 6.7.x before 6.7.3. Code to make security-relevant decisions about an established connection may execute too early, because the encrypted() signal has not yet been emitted and processed..

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Qt's HTTP/2 implementation has a timing vulnerability where security-relevant decisions about an established connection execute before the encrypted() signal is emitted and processed. This means code making TLS/encryption verification decisions may run on a connection that hasn't completed its security handshake, potentially allowing premature or insecure decisions on unverified connections.

MitigationUpgrade Qt to version 5.15.18 or later, 6.2.13 or later, 6.5.7 or later, or 6.7.3 or later to ensure security decisions execute only after the encrypted() signal is properly emitted and processed.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
QtApplication
Affected:< 5.15.18>= 6.0.0, < 6.2.13>= 6.3.0, < 6.5.7>= 6.6.0, < 6.7.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Qt installation and version
    Run 'qmake --version' or check the Qt library files (libQt5Core.so or libQt6Core.so) using 'ldd' or 'file' to locate the installed Qt version. On Linux, also check /usr/lib/x86_64-linux-gnu/cmake/Qt5/Qt5Config.cmake or similar package metadata.
    Affected if The installed Qt version is less than 5.15.18, or between 6.0.0 and 6.2.12, or between 6.3.0 and 6.5.6, or between 6.6.0 and 6.7.2.
  2. Verify HTTP/2 support is compiled in
    Check if the Qt build includes HTTP/2 support by examining QHttp2Configuration availability. In code, test if QNetworkRequest::Http2Allowed attribute is settable. Or check for 'QHttp2Configuration' class existence in the Qt installation headers or libraries.
    Affected if Qt is built with HTTP/2 support enabled (the vulnerability only affects HTTP/2 connections).
  3. Check for encrypted() signal usage in application code
    Search source code for connections to QNetworkAccessManager::encrypted() signal or QSslSocket::encrypted() signal. Look for patterns like 'connect(manager, &QNetworkAccessManager::encrypted, ...)' or similar signal-slot connections that perform TLS verification.
    Affected if Application code connects to the encrypted() signal to make security decisions about TLS/encryption verification.
  4. Inspect QNetworkAccessManager SSL configuration
    Examine the application code or configuration where QNetworkAccessManager is instantiated and check if custom QSslConfiguration is applied, particularly if encryption verification logic is tied to connection establishment.
    Affected if Code performs TLS certificate verification or other security decisions in connection handlers that may race with HTTP/2 stream establishment.

You are affected if your Qt version falls within the vulnerable ranges AND your application uses HTTP/2 with code that relies on the encrypted() signal for security decisions.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.15.18 / 6.2.13 / 6.5.7 or later
Fixed in 5.15.186.2.136.5.7
Interim mitigation

Upgrade Qt to version 5.15.18 or later, 6.2.13 or later, 6.5.7 or later, or 6.7.3 or later to ensure security decisions execute only after the encrypted() signal is properly emitted and processed.

Recommended fix High confidence

Qt 5.15.18, 6.2.13, 6.5.7, or 6.7.3 depending on your current major branch

  1. 1. Identify the current Qt version in use by checking project dependencies or Qt version macros (qVersion())
  2. 2. For Qt 5.15.x users: Upgrade to Qt 5.15.18 which contains the fix
  3. 3. For Qt 6.0.x - 6.2.x users: Upgrade to Qt 6.2.13 or later
  4. 4. For Qt 6.3.x - 6.5.x users: Upgrade to Qt 6.5.7 or later
  5. 5. For Qt 6.6.x - 6.7.x users: Upgrade to Qt 6.7.3 or later
  6. 6. Rebuild the application with the new Qt version
  7. 7. Test HTTP/2 functionality to verify the encrypted() signal now behaves correctly
Caveat Qt 6.x upgrades may have API or behavior changes; review the Qt 6.x change logs for your target version for any breaking changes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Qt Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing6.0 h
  • Review / QA3.0 h
18.0 hours of engineering $3,120
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-39936 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data