CVE-2025-5455: Possible denial of service when passing malformed data in a URL to qDecodeDataUrl
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 5.15.19 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.5.9 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.8.4 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.9.1
Event History
Frequently Asked Questions
What is the severity of CVE-2025-5455?
CVE-2025-5455 has been classified as a medium severity vulnerability.
How do I fix CVE-2025-5455?
To fix CVE-2025-5455, update your Qt installation to version 5.15.19 or above for version 5 or 6.5.9 or above for version 6.
What components are affected by CVE-2025-5455?
CVE-2025-5455 affects the qDecodeDataUrl() function in QtCore, primarily impacting QTextDocument and QNetworkReply.
Is CVE-2025-5455 exploitable?
Yes, CVE-2025-5455 can be exploited through malformed URLs with missing 'charset' values.
What versions of Qt are vulnerable to CVE-2025-5455?
CVE-2025-5455 affects Qt versions 5.15.0 to 5.15.18 and versions 6.0.0 to 6.9.0.