CVE-2025-5455: Qt

High severity, CVSS 8.4. EPSS: 0.4% chance of exploitation in the next 30 days.

An issue was found in the private API function qDecodeDataUrl() in QtCore, which is used in QTextDocument and QNetworkReply, and, potentially, in user code. If the function was called with malformed data, for example, an URL that contained a "charset" parameter that lacked a value (such as "data:charset,"), and Qt was built with assertions enabled, then it would hit an assertion, resulting in a denial of service (abort). This impacts Qt up to 5.15.18, 6.0.0->6.5.8, 6.6.0->6.8.3 and 6.9.0. This has been fixed in 5.15.19, 6.5.9, 6.8.4 and 6.9.1.

Affected products

• Qt Qt: up to and including 5.15.18; from 6.0.0, up to and including 6.5.8; from 6.6.0, up to and including 6.8.3; version 6.9.0 only

Published 2025-06-02. Last modified 2026-07-29.