CVE-2013-4549
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedQXmlSimpleReader in Qt before 5.2 allows context-dependent attackers to cause a denial of service (memory consumption) via an XML Entity Expansion (XEE) attack.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceQXmlSimpleReader in Qt before 5.2 does not properly limit XML entity expansion, allowing attackers to craft XML documents with recursive entity definitions that cause exponential memory consumption (Billion Laughs attack). This leads to denial of service through memory exhaustion when parsing malicious XML input.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 5.1.0= 5.0.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Qt libraries and versionSearch for Qt core libraries on the system. On Linux check /usr/lib/ and /usr/lib/x86_64-linux-gnu/. On Windows check Program Files directories. Run 'qmake -query QT_VERSION' if qmake is available, or inspect the Qt5Core.so or Qt5Core.dll file properties for version metadata.Affected if The installed Qt version is 5.0.2, 5.1.0, or any version in the 5.0.x series below 5.0.2, or any 5.1.x version at or below 5.1.0 (the exact version number depends on which Qt distribution is in use).
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Locate QXmlSimpleReader componentSearch for libQt5Xml.so (Linux), Qt5Xml.dll (Windows), or QtXml.framework (macOS) in the Qt installation directory or system library paths. This library contains the QXmlSimpleReader class.Affected if The QtXml library exists on the system and matches an affected Qt version range.
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Determine if application uses QXmlSimpleReaderReview application source code for usage of QXmlSimpleReader class, QXmlReader, or QXmlInputSource. Check build dependencies or library linking for QtXml. Search code for 'QXmlSimpleReader' or 'QXmlReader' class instantiation.Affected if The application code imports or uses Qt XML parsing classes from the QtXml module.
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Assess if application processes untrusted XML inputAnalyze the application's data flow for XML parsing operations. Identify whether XML data comes from network sources, file uploads, user input, or other untrusted origins. Review whether XML is parsed from external APIs, configuration files, or user-submitted content.Affected if The application parses XML input from sources outside the application's trusted boundary (network, users, external files).
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Check for XML entity expansion limits in applicationReview application code for custom entity expansion limits, XML parsing configuration, or input validation that restricts entity expansion. Inspect any XML parser configuration or preprocessing steps before QXmlSimpleReader is called.Affected if No application-layer entity expansion limits are implemented, and the Qt version is within the affected range.
A user is affected if their system has Qt version 5.0.2 or any Qt version at or below 5.1.0 (from Digia or the Qt project) AND their application uses QXmlSimpleReader to parse XML from untrusted sources without additional entity expansion limits.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade to Qt 5.2 or later which includes entity expansion limits. For systems unable to upgrade, implement application-layer XML input validation to reject or limit entity expansion before passing data to QXmlSimpleReader.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-4549 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2013-4549 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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