Fix trailing data handling with CertificateRevocationListBuilder.LoadPem. #122825
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…Pem. CRLBuilder.LoadPem asserted that the DER data read is the same amount as the decoded length of the data, however the DER reader does not enforce no trailing data, so this assert could be reached. This change blocks trailing data in the PEM, and changes the assert to an actual exception.
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Tagging subscribers to this area: @dotnet/area-system-security, @bartonjs, @vcsjones |
vcsjones
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Jan 2, 2026
...y/src/System/Security/Cryptography/X509Certificates/CertificateRevocationListBuilder.Load.cs
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Pull request overview
This PR fixes a security vulnerability in CertificateRevocationListBuilder.LoadPem where trailing data in PEM-encoded CRLs was not properly validated. The fix converts a Debug.Assert into a proper exception and adds test coverage for the scenario.
- Replaces
Debug.Assertwith proper validation that throwsCryptographicExceptionwhen trailing data is detected - Adds comprehensive test coverage for both string and ReadOnlySpan overloads of LoadPem with trailing data
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| CertificateRevocationListBuilder.Load.cs | Replaces Debug.Assert with proper exception throwing when bytesConsumed != bytesWritten |
| CrlBuilderTests.cs | Adds new test case LoadPem_TrailingData to verify trailing data is properly rejected |
bartonjs
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Jan 2, 2026
This was referenced Jan 3, 2026
stephentoub
approved these changes
Jan 3, 2026
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/ba-g deadletter |
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CRLBuilder.LoadPem asserted that the DER data read is the same amount as the decoded length of the data, however the DER reader does not enforce no trailing data, so this assert could be reached.
This change blocks trailing data in the PEM, and changes the assert to an actual exception.
Fixes #122823