Executive brief
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.
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