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Fix preserving %2F at HTTP/1 absolute-form request #65930

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Merged
DeagleGross merged 6 commits into from
Apr 13, 2026
+34 −1
Merged

Fix preserving %2F at HTTP/1 absolute-form request #65930

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1ad18d9
Fix path canonicalization inconsistency between origin-form and absol…
DeagleGross Mar 23, 2026
ed8a1d2
Fix path canonicalization inconsistency between origin-form and absol…
DeagleGross Mar 23, 2026
8e5caf2
Add renting of pathBuffer to improve
DeagleGross Mar 23, 2026
003c8ba
Merge branch 'dmkorolev/kestrel-absolute-form-path-canonicalization' …
DeagleGross Mar 23, 2026
c5653c3
handle exception
DeagleGross Mar 23, 2026
84600ad
address PR comments
DeagleGross Mar 24, 2026
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31 changes: 30 additions & 1 deletion src/Servers/Kestrel/Core/src/Internal/Http/Http1Connection.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
using System.Buffers;
using System.Diagnostics;
using System.IO.Pipelines;
using System.Text;
using Microsoft.AspNetCore.Connections;
using Microsoft.AspNetCore.Connections.Features;
using Microsoft.AspNetCore.Http;
Expand Down Expand Up @@ -667,7 +668,35 @@ private void OnAbsoluteFormTarget(TargetOffsetPathLength targetPath, Span<byte>
}

_absoluteRequestTarget = _parsedAbsoluteRequestTarget = uri;
Path = _parsedPath = uri.LocalPath;

// Use PathDecoder.DecodePath (same as origin-form and HTTP/2/3) instead of
// uri.LocalPath, which decodes %2F to '/' breaking path canonicalization.
const int MaxPathBufferStackAllocSize = 256;

var absolutePath = uri!.AbsolutePath;
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byte[]? rentedBuffer = null;
Span<byte> pathBuffer = absolutePath.Length <= MaxPathBufferStackAllocSize
? (stackalloc byte[MaxPathBufferStackAllocSize])
: (rentedBuffer = ArrayPool<byte>.Shared.Rent(absolutePath.Length));
var pathBufferSliced = pathBuffer[..absolutePath.Length];

try
{
Encoding.ASCII.GetBytes(absolutePath, pathBufferSliced);
Path = _parsedPath = PathDecoder.DecodePath(pathBufferSliced, targetPath.IsEncoded, absolutePath, query.Length);
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}
catch (InvalidOperationException)
{
ThrowRequestTargetRejected(target);
}
finally
{
if (rentedBuffer is not null)
{
ArrayPool<byte>.Shared.Return(rentedBuffer);
}
}

// don't use uri.Query because we need the unescaped version
previousValue = _parsedQueryString;
if (disableStringReuse ||
Expand Down
4 changes: 4 additions & 0 deletions src/Servers/Kestrel/Core/test/StartLineTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -183,6 +183,8 @@ public void DifferentFormsWorkTogether()
[InlineData("/?q=123&w=xyz", "/", "?q=123&w=xyz")]
[InlineData("/path?q=123&w=xyz", "/path", "?q=123&w=xyz")]
[InlineData("/path%20with%20space?q=abc%20123", "/path with space", "?q=abc%20123")]
[InlineData("/a%2Fb", "/a%2Fb", "")]
[InlineData("/a%2Fb?q=1", "/a%2Fb", "?q=1")]
public void OriginForms(string rawTarget, string path, string query)
{
Http1Connection.Reset();
Expand Down Expand Up @@ -277,6 +279,8 @@ public void OriginForms(string rawTarget, string path, string query)
[InlineData("http://localhost/?q=123&w=xyz", "/", "?q=123&w=xyz")]
[InlineData("http://localhost/path?q=123&w=xyz", "/path", "?q=123&w=xyz")]
[InlineData("http://localhost/path%20with%20space?q=abc%20123", "/path with space", "?q=abc%20123")]
[InlineData("http://localhost/a%2Fb", "/a%2Fb", "")]
[InlineData("http://localhost/a%2Fb?q=1", "/a%2Fb", "?q=1")]
public void AbsoluteForms(string rawTarget, string path, string query)
{
Http1Connection.Reset();
Expand Down
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