encodeText in QDom in Qt before 6.8.0 has a complex algorithm involving XML string copy and inline replacement of parts of a string (with relocation of later data).

Improper output neutralization (XML injection) in QDom comment, CDATA, and processing-instruction serialization in Qt XML from 4.0.0 through 6.11 allows untrusted text serialized by an application into those nodes to inject arbitrary XML markup, because the node terminators are not escaped under the default InvalidDataPolicy (AcceptInvalidChars). Fixed in Qt 6.12.

A type confusion vulnerability in Qt SVG allows an attacker to cause an application crash via a crafted SVG image.

When processing SVG marker references, the renderer retrieves a node by its id attribute and casts it to QSvgMarker without verifying the node type. A non-marker element (such as a <line> element) that references itself as a marker triggers an out-of-bounds heap read due to the object size difference between QSvgLine and QSvgMarker, followed by an endless recursion that bypasses the marker recursion guard through incorrect virtual dispatch. The result is an application crash (denial of service).

This issue affects Qt SVG:  from 6.7.0 before 6.8.8, from 6.9.0 before 6.11.1.

When passing values outside of the expected range to QColorTransferGenericFunction it can cause a denial of service, for example, this can happen when passing a specifically crafted ICC profile to QColorSpace::fromICCProfile.

This issue affects Qt from 6.6.0 through 6.8.3, from 6.9.0 through 6.9.1. This is fixed in 6.8.4 and 6.9.2.

There is a "Use After Free" vulnerability in Qt's QHttp2ProtocolHandler in the QtNetwork module. This only affects HTTP/2 handling, HTTP handling is not affected by this at all. This happens due to a race condition between how QHttp2Stream uploads the body of a POST request and the simultaneous handling of HTTP error responses.

This issue only affects Qt 6.9.0 and has been fixed for Qt 6.9.1.

Insufficient validation of node IDs in Qt SVG module allows arbitrary QML/JavaScript code injection when loading malicious SVG files through the VectorImage component in Qt Quick. While QML execution is typically more restricted than native code execution, this could still lead to denial of service, information disclosure, or other impacts depending on the application's privilege level and data access.

The module will parse a <pattern> node which is not a child of a structural node. The node will be deleted after creation but might be accessed later leading to a use after free.

Uncontrolled recursion in Qt SVG module

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.

When loading a specifically crafted ICNS format image file in QImage then it will trigger a crash.

This issue affects Qt from versions 6.3.0 through 6.5.9, from 6.6.0 through 6.8.4, 6.9.0. This is fixed in 6.5.10, 6.8.5 and 6.9.1.

There is a Heap-based Buffer Overflow vulnerability in QTextMarkdownImporter. This requires an incorrectly formatted markdown file to be passed to QTextMarkdownImporter to trigger the overflow.

This issue affects Qt from 6.8.0 to 6.8.4. Versions up to 6.6.0 are known to be unaffected, and the fix is in 6.8.4 and later.

Improper Link Resolution Before File Access ('Link Following') vulnerability in QFileSystemEngine in the Qt corelib module on Windows which potentially allows Symlink Attacks and the use of Malicious Files. Issue originates from CVE-2024-38081. The vulnerability arises from the use of the GetTempPath API, which can be exploited by attackers to manipulate temporary file paths, potentially leading to unauthorized access and privilege escalation. The affected public API in the Qt Framework is QDir::tempPath() and anything that uses it, such as QStandardPaths with TempLocation, QTemporaryDir, and QTemporaryFile.

This issue affects all version of Qt up to and including 5.15.18, from 6.0.0 through 6.5.8, from 6.6.0 through 6.8.1. It is fixed in Qt 5.15.19, Qt 6.5.9, Qt 6.8.2, 6.9.0

An out-of-bounds read (buffer over-read) vulnerability exists in QTextCodec::codecForName() in Qt. When the function is called with a QByteArray that is not NUL-terminated (for example, one created with QByteArray::fromRawData()), the codec-name matching routine reads past the end of the supplied buffer. In most cases this results in an incorrect text codec being selected; in the worst case, if the over-read reaches unmapped memory, the process crashes (denial of service). The over-read is bounded by the length of the longest codec-name candidate, and the out-of-bounds bytes are only compared internally against Qt's fixed list of codec names, so no data is disclosed to an attacker. Applications that do not pass non-NUL-terminated QByteArrays to QTextCodec::codecForName() are not exposed. The affected code resides in the Qt5Compat module from Qt 6.0.0 onward, and in Qt Core (qtbase) in Qt 4.x and Qt 5.x.

An issue was discovered in Qt before 5.15.15, 6.x before 6.2.10, and 6.3.x through 6.5.x before 6.5.3. There are infinite loops in recursive entity expansion.

An issue was discovered in Qt before 5.15.15, 6.x before 6.2.9, and 6.3.x through 6.5.x before 6.5.2. Certificate validation for TLS does not always consider whether the root of a chain is a configured CA certificate.

An issue was discovered in Qt 5.x before 5.15.14, 6.x before 6.2.9, and 6.3.x through 6.5.x before 6.5.1. QDnsLookup has a buffer over-read via a crafted reply from a DNS server.

Qt 5.x before 5.15.6 and 6.x through 6.1.2 has an out-of-bounds write in QOutlineMapper::convertPath (called from QRasterPaintEngine::fill and QPaintEngineEx::stroke).

Insufficient validation of node IDs in Qt SVG module allows arbitrary QML/JavaScript code injection when loading malicious SVG files through the VectorImage component in Qt Quick. While QML execution is typically more restricted than native code execution, this could still lead to denial of service, information disclosure, or other impacts depending on the application's privilege level and data access.

A stack overflow (stack exhaustion) flaw was found in the way Qt parsed XML input with several nested opening tags. An application using Qt's QXmlSimpleReader to parse specially crafted XML input could crash.

The GIF decoder in QtGui in Qt before 5.3 allows remote attackers to cause a denial of service (NULL pointer dereference) via invalid width and height values in a GIF image.

Integer overflow in Qt 3.3 before 3.3.7, 4.1 before 4.1.5, and 4.2 before 4.2.1, as used in the KDE khtml library, kdelibs 3.1.3, and possibly other packages, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted pixmap image.

Qt 6 through 6.6 was discovered to contain a NULL pointer dereference via the function QXcbConnection::initializeAllAtoms(). NOTE: this is disputed because it is not expected that an X application should continue to run when there is arbitrary anomalous behavior from the X server.

Last updated 25 August 2025

In Qt through 5.14.1 the WebSocket implementation accepts up to 2GB for frames and 2GB for messages. Smaller limits cannot be configured. This makes it easier for attackers to cause a denial of service (memory consumption).

Qt before 6.4.3 allows a denial of service via a crafted string when the SQL ODBC driver plugin is used and the size of SQLTCHAR is 4. The affected versions are 5.x before 5.15.13, 6.x before 6.2.8, and 6.3.x before 6.4.3.

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..

QAbstractOAuth in Qt Network Authorization in Qt before 5.15.17, 6.x before 6.2.13, 6.3.x through 6.5.x before 6.5.6, and 6.6.x through 6.7.x before 6.7.1 uses only the time to seed the PRNG, which may result in guessable values.

An issue was discovered in gui/util/qktxhandler.cpp in Qt before 5.15.17 6.x before 6.2.12 6.3.x through 6.5.x before 6.5.5 and 6.6.x before 6.6.2. A buffer overflow and application crash can occur via a crafted KTX image file.

QLowEnergyController in Qt before 6.8.2 mishandles malformed Bluetooth ATT commands, leading to an out-of-bounds read (or division by zero). This is fixed in 5.15.19, 6.5.9, and 6.8.2.

An issue was discovered in Qt before 5.15.15, 6.x before 6.2.9, and 6.3.x through 6.5.x before 6.5.1. When a SVG file with an image inside it is rendered, a QTextLayout buffer overflow can be triggered.