Is CVE-2026-9499 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-9499 being exploited in the wild.

How severe is CVE-2026-9499?

Informational severity, with a CVSS score of 6.3, published 21 July 2026.

Which products and versions are affected?

The Qt Company Qt5Compat 6.0.0 to 6.8.7, 6.9.0 to 6.11.0; The Qt Company Qtbase 4.x, 5.x.

Is there a fix for CVE-2026-9499?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-9499 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-9499?

Check whether you run The Qt Company Qt5Compat or The Qt Company Qtbase at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-9499: Qt QTextCodec out-of-bounds read in codecForName

CVE-2026-9499 · Severity: info · CVSS 6.3 · Published 2026-07-21

A vulnerability exists in the Qt software framework, which is widely used to build cross-platform applications. Under specific conditions when processing text data, the software may read beyond its intended memory limits, potentially causing the application to crash. While this issue does not lead to data theft, it can disrupt business operations by causing service outages for affected applications.

Vendors: The Qt Company.

Quick answers

Is CVE-2026-9499 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-9499 being exploited in the wild.
How severe is CVE-2026-9499?: Informational severity, with a CVSS score of 6.3, published 21 July 2026.
Which products and versions are affected?: The Qt Company Qt5Compat 6.0.0 to 6.8.7, 6.9.0 to 6.11.0; The Qt Company Qtbase 4.x, 5.x.
Is there a fix for CVE-2026-9499?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-9499 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-9499?: Check whether you run The Qt Company Qt5Compat or The Qt Company Qtbase at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An out-of-bounds read (CWE-125) exists in QTextCodec::codecForName() within the Qt framework. The vulnerability is triggered when the function is passed a QByteArray that is not NUL-terminated (e.g., via QByteArray::fromRawData()), causing the codec-name matching routine to read past the buffer end. The over-read is limited to the length of the longest codec-name candidate and is only compared against internal fixed lists, preventing data disclosure. The primary impact is a potential process crash (Denial of Service) if the read hits unmapped memory, or the selection of an incorrect text codec. The issue affects Qt 4.x and 5.x (qtbase) and Qt 6.x (Qt5Compat).

Affected products

Qt Qt (Qt5Compat module) 6.0.0 to 6.8.7, 6.9.0 to 6.11.0
Qt Qt (qtbase module) 4.x, 5.x

Timeline

2026-07-21: disclosed
2026-07-21: advisory

References

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