Prevent xml DoS attacks#6419
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Pull request overview
This PR hardens DARC’s XML parsing for dependency/version files against DTD-based entity expansion attacks (e.g., “billion laughs”) by prohibiting DTD processing and disabling XML resolvers, with a regression test to validate the behavior.
Changes:
- Updated XML-loading helpers to use
XmlReaderwith secureXmlReaderSettings(DtdProcessing = Prohibit,XmlResolver = null) instead ofXmlDocument.LoadXml. - Applied the same protection in both
DependencyFileManagerandVersionDetailsParserXML parsing paths. - Added a unit test to ensure DTD/entity-expansion payloads are rejected.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| test/Darc/Microsoft.DotNet.DarcLib.Tests/Helpers/DependencyFileManagerTests.cs | Adds coverage verifying DTD/entity-expansion XML is rejected. |
| src/Microsoft.DotNet.Darc/DarcLib/Helpers/VersionDetailsParser.cs | Switches XML loading to a secure XmlReader configuration to prohibit DTDs. |
| src/Microsoft.DotNet.Darc/DarcLib/Helpers/DependencyFileManager.cs | Switches XML loading to a secure XmlReader configuration to prohibit DTDs. |
premun
approved these changes
Jun 22, 2026
premun
approved these changes
Jun 22, 2026
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| var readerSettings = new XmlReaderSettings | ||
| { | ||
| DtdProcessing = DtdProcessing.Prohibit, | ||
| XmlResolver = null | ||
| }; |
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| var readerSettings = new XmlReaderSettings | ||
| { | ||
| DtdProcessing = DtdProcessing.Prohibit, | ||
| XmlResolver = null | ||
| }; |
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| using var reader = XmlReader.Create(new StringReader(fileContent), readerSettings); | ||
| document.Load(reader); |
premun
approved these changes
Jun 22, 2026
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https://dev.azure.com/dnceng/internal/_workitems/edit/11169