A defect in the Qt for MCUs core string handling causes heap memory corruption. When an application passes text into Qt Quick Ultralite using the public Qul::String interface type, and that text is held in a std::string, the conversion to the internal string type copies the pointer without taking ownership of it. Two objects then release the same memory, producing a double free, an invalid free, or a use-after-free.

Out-of-bounds read vulnerability in Context2D.path and PathSvg.path properties impacts Qt Quick

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.

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.

There is an incomplete cleanup vulnerability in Qt Network's Schannel support on Windows which can lead to a Denial of Service over a long period.

This issue affects Qt from 5.15.0 through 6.8.3, from 6.9.0 before 6.9.2.

An issue was discovered in the HTTP2 implementation in Qt before 5.15.17, 6.x before 6.2.11, 6.3.x through 6.5.x before 6.5.4, and 6.6.x before 6.6.2. network/access/http2/hpacktable.cpp has an incorrect HPack integer overflow check.

Uncontrolled recursion in Qt SVG module

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.

An issue has been fixed in Qt versions 5.14.0 where QPluginLoader attempts to load plugins relative to the working directory, allowing attackers to execute arbitrary code via crafted files.

Last updated 25 August 2025

In Qt for MCUs, a Text element that displays styled text halts the device if an <img> tag in the text contains an attribute with an empty value. The text parser passes the empty value to an internal check that only accepts non-empty values. The check fails and reports an error, and the default error handler halts the device.

Strings optimized for Latin-1 displaying Latin-1 characters cause incorrect String.arg() formatting by an incorrect buffer size calculation, causing out-of-bounds reading.

Authentication bypass vulnerability in the password authentication mechanism of the Qt VNC Server module. An attacker using a specially modified VNC client that violates the RFB protocol can bypass Qt VNC Server's password authentication and gain unauthorized remote access to the shared application, compromising the confidentiality and integrity of the session.

Uncontrolled recursion (CWE-674) in the QDomDocument/QDomNode serialization path of the Qt XML module (QtXml, qtbase). QDomElementPrivate::save() and QDomNodePrivate::save() recurse mutually, consuming one stack frame per level of element nesting with no depth limit, no configurable bound and no error return. A document with deeply nested elements parses successfully but exhausts the call stack and terminates the process when serialized. Reachable via QDomDocument::toByteArray() (Qt 4.0 and later), QDomDocument::toString(), QDomDocument::toCString(), QDomNode::save(), and operator<<(QTextStream&, const QDomNode&). Denial of service only — no code execution and no memory disclosure.

An out-of-bounds read in Qt NFC's language code length parsing allows a physically proximate attacker to cause a denial of service or limited memory disclosure via a crafted NFC tag.

QDomDocument XML parsing is vulnerable to a remotely-triggerable denial-of-service crash when processing untrusted input.

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.

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).