HttpHeaders: reject Content-Length with leading + or - sign#67635
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DeagleGross wants to merge 6 commits into
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HttpHeaders: reject Content-Length with leading + or - sign#67635DeagleGross wants to merge 6 commits into
+ or - sign#67635DeagleGross wants to merge 6 commits into
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RFC 9112 section 6.2 defines Content-Length as 1*DIGIT. The HTTP/1.1 request header parser used Utf8Parser.TryParse<long>, which accepts a leading '+' or '-' sign. Values like '+123' or '-0' were therefore accepted (parsed as 123 and 0) instead of being rejected with 400 Bad Request. The custom-encoding path used long.TryParse with NumberStyles.Integer, which also allows a leading sign, so it had the same defect. Add a leading-digit check on the byte path and switch the custom-encoding path to NumberStyles.None. Extend BadRequestIfContentLengthInvalid to cover '+1', '+0', '-0'.
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Pull request overview
This PR tightens Kestrel’s Content-Length parsing to align with RFC 9110 §8.6 (Content-Length = 1*DIGIT) by rejecting values that Utf8Parser.TryParse would otherwise accept due to leading sign handling.
Changes:
- Reject
Content-Lengthvalues that start with+or-in the fast-path byte parsing. - Tighten the custom-encoding parsing path by switching from
NumberStyles.IntegertoNumberStyles.Noneto disallow signs/whitespace. - Extend functional tests to cover
+1,+0, and-0invalid values.
Show a summary per file
| File | Description |
|---|---|
| src/Servers/Kestrel/test/InMemory.FunctionalTests/BadHttpRequestTests.cs | Adds coverage for signed Content-Length values that must now be rejected. |
| src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestHeaders.cs | Adds leading-sign rejection in the byte parsing path and tightens the custom-encoding parsing style. |
Copilot's findings
- Files reviewed: 2/2 changed files
- Comments generated: 1
BrennanConroy
approved these changes
Jul 8, 2026
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Per RFC 9110 8.6
Content-Lengthis1*DIGIT, butUtf8Parser.TryParse()accepts leading+or-, which accepts values such as+1. Added a guard to dissallow leading+or-.