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[release/8.0] Fix: hardening http2 to refuse newline chars on trailers and dynamic HPACK table #69250

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Merged
SamMonoRT merged 3 commits into from
Sep 14, 2026
Merged

[release/8.0] Fix: hardening http2 to refuse newline chars on trailers and dynamic HPACK table #69250

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cb35195
Fix: hardening http2 to refuse newline chars on trailers and dynamic …
amf-fs Sep 9, 2026
71faa33
Fix flaky HTTP/3 request trailers test
BrennanConroy Sep 11, 2026
b9927d5
Update Http2StreamTests to remove invalid assertion
BrennanConroy Sep 11, 2026
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2 changes: 1 addition & 1 deletion src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -544,7 +544,7 @@ public void OnTrailer(ReadOnlySpan<byte> name, ReadOnlySpan<byte> value)
IncrementRequestHeadersCount();

string key = name.GetHeaderName();
var valueStr = value.GetRequestHeaderString(key, HttpRequestHeaders.EncodingSelector, checkForNewlineChars: false);
var valueStr = value.GetRequestHeaderString(key, HttpRequestHeaders.EncodingSelector, checkForNewlineChars: true);
RequestTrailers.Append(key, valueStr);
}

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2 changes: 1 addition & 1 deletion src/Servers/Kestrel/Core/src/Internal/Http2/Http2Connection.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1527,7 +1527,7 @@ private void OnHeaderCore(HeaderType headerType, int? staticTableIndex, ReadOnly
{
UpdateHeaderParsingState(value, GetPseudoHeaderField(name));

_currentHeadersStream.OnHeader(name, value, checkForNewlineChars: false);
_currentHeadersStream.OnHeader(name, value, checkForNewlineChars: true);
}
break;
case HeaderType.NameAndValue:
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49 changes: 35 additions & 14 deletions src/Servers/Kestrel/test/InMemory.FunctionalTests/Http2/Http2ConnectionTests.cs
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Expand Up @@ -5591,25 +5591,46 @@ public static TheoryData<byte[], string> IllegalTrailerData
get
{
// We can't use HPackEncoder here because it will convert header names to lowercase
var data = new TheoryData<byte[], string>();
var data = new TheoryData<byte[], string>
{
// Indexed Header Field - :method: GET
{ new byte[] { 0x82 }, CoreStrings.HttpErrorTrailersContainPseudoHeaderField },

// Indexed Header Field - :method: GET
data.Add(new byte[] { 0x82 }, CoreStrings.HttpErrorTrailersContainPseudoHeaderField);
// Indexed Header Field - :path: /
{ new byte[] { 0x84 }, CoreStrings.HttpErrorTrailersContainPseudoHeaderField },

// Indexed Header Field - :path: /
data.Add(new byte[] { 0x84 }, CoreStrings.HttpErrorTrailersContainPseudoHeaderField);
// Indexed Header Field - :scheme: http
{ new byte[] { 0x86 }, CoreStrings.HttpErrorTrailersContainPseudoHeaderField },

// Indexed Header Field - :scheme: http
data.Add(new byte[] { 0x86 }, CoreStrings.HttpErrorTrailersContainPseudoHeaderField);
// Literal Header Field without Indexing - Indexed Name - :authority: 127.0.0.1
{
new byte[] { 0x01, 0x09 }.Concat(Encoding.ASCII.GetBytes("127.0.0.1")).ToArray(),
CoreStrings.HttpErrorTrailersContainPseudoHeaderField
},

// Literal Header Field without Indexing - Indexed Name - :authority: 127.0.0.1
data.Add(new byte[] { 0x01, 0x09 }.Concat(Encoding.ASCII.GetBytes("127.0.0.1")).ToArray(), CoreStrings.HttpErrorTrailersContainPseudoHeaderField);
// Literal Header Field without Indexing - New Name - contains-Uppercase: 0
{
new byte[] { 0x00, 0x12 }.Concat(Encoding.ASCII.GetBytes("contains-Uppercase")).Concat(new byte[] { 0x01, (byte)'0' }).ToArray(),
CoreStrings.HttpErrorTrailerNameUppercase
},

//Invalid header CR - contains-cr: \r
{
new byte[]{0x00, 0x0B}.Concat(Encoding.ASCII.GetBytes("contains-cr")).Concat(new byte[]{0x01, 0x0D}).ToArray(),
CoreStrings.BadRequest_MalformedRequestInvalidHeaders
},

// Literal Header Field without Indexing - New Name - contains-Uppercase: 0
data.Add(new byte[] { 0x00, 0x12 }
.Concat(Encoding.ASCII.GetBytes("contains-Uppercase"))
.Concat(new byte[] { 0x01, (byte)'0' })
.ToArray(), CoreStrings.HttpErrorTrailerNameUppercase);
//Invalid header LF - contains-lf: \n
{
new byte[]{0x00, 0x0B}.Concat(Encoding.ASCII.GetBytes("contains-lf")).Concat(new byte[]{0x01, 0x0A}).ToArray(),
CoreStrings.BadRequest_MalformedRequestInvalidHeaders
},
//Invalid header CR and LF - contains-crlf: \r\n
{
new byte[]{0x00, 0x0D}.Concat(Encoding.ASCII.GetBytes("contains-crlf")).Concat(new byte[]{0x02, 0x0D, 0x0A}).ToArray(),
CoreStrings.BadRequest_MalformedRequestInvalidHeaders
}
};

return data;
}
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26 changes: 26 additions & 0 deletions src/Servers/Kestrel/test/InMemory.FunctionalTests/Http2/Http2StreamTests.cs
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Expand Up @@ -5374,4 +5374,30 @@ await ExpectAsync(Http2FrameType.RST_STREAM,
Assert.Contains("date", _decodedHeaders.Keys, StringComparer.OrdinalIgnoreCase);
Assert.Equal("200", _decodedHeaders[InternalHeaderNames.Status]);
}

[Theory]
[InlineData("\r")]
[InlineData("\n")]
[InlineData("\r\n")]
public async Task OnDynamicIndexedHeader_NewlineCharactersInValue_ThrowsConnectionError(string newlineCharacters)
{
await InitializeConnectionAsync(_noopApplication);

// Start a request header block without END_HEADERS so the connection has an active stream receiving headers.
await SendHeadersAsync(streamId: 1, flags: Http2HeadersFrameFlags.END_STREAM, headers: _browserRequestHeaders);

var value = Encoding.ASCII.GetBytes(newlineCharacters);

// Simulate HPackDecoder resolving a fully indexed dynamic-table entry.
var exception = Assert.Throws<Http2ConnectionErrorException>(() =>
_connection.OnDynamicIndexedHeader(index: null, name: "contains-newline"u8, value));

Assert.Equal(Http2ErrorCode.PROTOCOL_ERROR, exception.ErrorCode);

Assert.Contains(CoreStrings.BadRequest_MalformedRequestInvalidHeaders, exception.Message);

// Finish the intentionally incomplete header block and shut down normally.
await SendEmptyContinuationFrameAsync(streamId: 1, flags: Http2ContinuationFrameFlags.END_HEADERS);
await StopConnectionAsync(expectedLastStreamId: 1, ignoreNonGoAwayFrames: true);
}
}
27 changes: 27 additions & 0 deletions src/Servers/Kestrel/test/InMemory.FunctionalTests/Http3/Http3StreamTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2028,6 +2028,33 @@ public async Task RequestTrailers_CanReadTrailersFromRequest()
await requestStream.ExpectReceiveEndOfStream();
}

[Theory]
[InlineData("\r")]
[InlineData("\n")]
[InlineData("\r\n")]
public async Task RequestTrailers_ContainsNewlines(string newlineChars)
{

var headers = new[]
{
new KeyValuePair<string, string>(InternalHeaderNames.Method, "GET"),
new KeyValuePair<string, string>(InternalHeaderNames.Path, "/"),
new KeyValuePair<string, string>(InternalHeaderNames.Scheme, "http"),
};

var trailerWithNewlines = new[]
{
new KeyValuePair<string, string>("contains-newlines", newlineChars),
};

var requestStream = await Http3Api.InitializeConnectionAndStreamsAsync(_echoApplication, headers, endStream: false);
await requestStream.SendHeadersAsync(trailerWithNewlines, endStream: true);

await requestStream.WaitForStreamErrorAsync(
Http3ErrorCode.MessageError,
expectedErrorMessage: CoreStrings.BadRequest_MalformedRequestInvalidHeaders);
}

[Fact]
public async Task FrameAfterTrailers_UnexpectedFrameError()
{
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