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node:http, node:http2: refuse the malformed requests that Node refuses - #46456
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Updated 3:05 AM PT - Oct 22nd, 2026
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WalkthroughThe node:http parser now rejects invalid request-target bytes and DEL in header and trailer values. Invalid request targets produce HTTP 400 responses and map to ChangesNode HTTP request parsing
HTTP/2 content-length validation
Suggested reviewers: Priority: ➖ Normal Merge Risk: 🔵 Low · up to
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| Check name | Status | Explanation |
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| Title check |  |
The title clearly summarizes the main change: node:http and node:http2 now reject malformed requests that Node rejects. |
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Check skipped because no linked issues were found for this pull request. |
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The pull request description includes both required sections: “What does this PR do?” and “How did you verify your code works?”. It provides detailed behavior changes, scope, compatibility notes, and … |
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The pull request description includes both required sections: “What does this PR do?” and “How did you verify your code works?”. It provides detailed behavior changes, scope, compatibility notes, and verification results.
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Actionable comments posted: 1
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Inline comments:
Review comments at @packages/bun-uws/src/HttpParser.h:
- Around line 970-971: Update the request-target validation in the request-line
parser so a CR not followed by LF returns INVALID_URL, while preserving
acceptance of a valid request-line terminator. Keep the existing behavior for
other URL bytes and locate the change around the IsNodeHttp check that returns
ConsumeRequestLineResult::error(HTTP_HEADER_PARSER_ERROR_INVALID_URL).
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📒 Files selected for processing: 5
packages/bun-uws/src/HttpParser.hsrc/js/node/_http_server.tssrc/jsc/bindings/ErrorCode.tssrc/jsc/bindings/NodeHTTP.cpptest/js/node/http/node-http.test.ts
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Beyond the inline findings, I also checked that the IsNodeHttp=false instantiation used by Bun.serve is behavior-preserving: every new DEL/control check in consumeRequestLine, tryConsumeFieldValue and getHeaders is gated on the template bool, so the hasDelete SWAR test and the post-scan stop-byte check compile out there. Two further candidates were ruled out: a DEL byte in the target reaching the handler past the new check (the byte-wise and word-wise paths cover both positions), and a CONNECT authority starting with a byte >= 0x80 (accepted and percent-encoded as the PR describes, not a crash or bypass).
Extended reasoning...
The change touches the shared uWS HTTP request parser (packages/bun-uws/src/HttpParser.h), the node:http req.url construction in src/jsc/bindings/NodeHTTP.cpp, the mirrored parser-error enum in src/js/node/_http_server.ts and the ErrorCode registry, plus four new tests. It is security-relevant parsing of untrusted wire bytes with a user-visible behavior change to req.url for non-ASCII targets. Confirmed inline findings (lenient-parser trailer regression, unbounded expansion with maxHeaderSize 0, non-ASCII route matching break) mean a human must weigh the compat trade-off, so this is not approvable.
…the request target's length
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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.
Beyond the inline nit, I also checked the two follow-up commits: the target-length clamp in consumeRequestLine now fires for both maxHeaderSize: 0 and any value above INT32_MAX / 3, and the final data - start > maxHeaderSize check (HttpParser.h:970) bounds the accepted target at 715,827,882 bytes, so the 3x percent-encoded req.url stays under String::MaxLength even with an explicit large limit. The new takeRequestTrailers predicate in src/js/internal/http.ts matches serverLenientFlags (bit 0 is set for both "relaxed" and "insecure"), and the new test's lenient matrix exercises all three spellings for header and trailer DEL.
Extended reasoning...
The range adds four commits to node:http request parsing: template-gated DEL/CTL rejection in the request target and header/trailer values, a percent-encoding path for non-ASCII target bytes in NodeHTTP.cpp, a new HPE_INVALID_URL error code, and a trailer-leniency fix in internal/http.ts. It touches the network-facing HTTP parser (adversarial wire input), which is security-sensitive. The two later commits address the trailer-leniency and StringBuilder-overflow concerns raised in the prior review; one inline nit on lenient-mode test coverage for the target scan remains, and the req.url encoding change is a documented behavioral change for raw-byte clients that a maintainer should weigh.
Jarred-Sumner
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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.
Beyond the inline finding, I also checked the new SWAR scan in packages/bun-uws/src/HttpParser.h: hasDeleteOrAbove can carry out of a 0xff byte into its neighbor, but that byte is already flagged by its own high bit, so the nonzero/zero result stays exact; and the per-word check only runs on words with no byte below 33, so the post-padded CR sentinel never reaches it and a fragmented request line still short-reads rather than returning 400. The HTTP_PARSER_ERROR_INVALID_URL = 18 / HTTP_HEADER_PARSER_ERROR_INVALID_URL = 6 values are mirrored only in HttpParser.h and src/js/node/_http_server.ts and both are in sync, and the trailer leniency bit in src/js/internal/http.ts now matches serverLenientFlags. Note that the PR title and description still describe the percent-encoding of req.url that was dropped in 8526ce5; the current diff rejects those targets instead.
Extended reasoning...
The current diff no longer touches src/jsc/bindings/NodeHTTP.cpp: the request-target handling moved from percent-encoding bytes >= 0x80 to rejecting any byte >= 0x7f with a new HPE_INVALID_URL, DEL now ends header and trailer values in node:http mode, and the trailer re-parse uses the same lenient flags as the native parser. This is wire-facing parser code on the node:http server, so the SWAR helpers and the post-padding interaction were checked directly and hold up; the one confirmed finding (raw non-ASCII clients now receive 400 where the base branch served them) is posted inline, and the PR description is stale relative to the code, so a human should weigh that compatibility decision.
Jarred-Sumner
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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.
Beyond the inline findings, I also checked two things in this push and ruled them out: the hasDeleteOrAbove SWAR helper is exact for "any byte >= 0x7f" (the only bytes that carry into a neighbor, 0xfe and 0xff, are already flagged by x itself, so a spurious 0x80 in the neighbor cannot change the nonzero result), and the hardcoded tryConsumeFieldValue<true> in parseTrailerFields is reached only from validateNodeTrailerSection (gated on IsNodeHttp) and JSNodeHTTPServerSocket.cpp, so the Bun.serve parser instantiation does not pick up the DEL stop.
Extended reasoning...
The diff templates the uWS request-line and field-value scanners on IsNodeHttp, adds HPE_INVALID_URL plumbing through _http_server.ts and ErrorCode.ts, switches the trailer re-parse leniency to calculateLenientFlags, and adds a server-side content-length overrun RST_STREAM in the h2 connection. It touches request parsing of untrusted wire bytes; the new SWAR checks and the trailer-parser template argument were verified against the code paths that reach them, and the Bun.serve instantiation stays byte-identical because every new branch is under if constexpr (IsNodeHttp).
Additional findings (outside the current diff — GitHub can't attach inline comments there):
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src/runtime/api/bun/h2/connection.rs— pre-existing: a Bun http2 client still accepts a response body longer than its declared content-length, where Node's client resets the stream with PROTOCOL_ERROR. The new body_exceeds_content_length() check only fires on the server because content_length is stored underself.is_serverat connection.rs:1394-1398, and enforce_content_length returns early for clients at connection.rs:1728. Fix: apply the same DATA accounting on the client side with nghttp2's response exemptions (skip 1xx, no limit for a 2xx to CONNECT, expected length 0 for 204/304 and for HEAD), so both ends of the engine reject excess DATA; the server-side sites at connection.rs:1531 and :1661 stay as they are.Why this was flagged
A Bun http2 client (http2.connect, src/runtime/api/bun/h2_frame_parser.rs:3600 creates the engine with is_server=false) requests a resource and the server answers with
content-length: 5followed by 12 bytes of DATA. In finish_header_block the declared length is only recorded whenself.is_server(connection.rs:1394-1398), so the client stream's content_length stays None and body_exceeds_content_length() (connection.rs:68) is false on every DATA frame; enforce_content_length also returns false for clients (connection.rs:1728). The 12 bytes are delivered and the response ends normally. Node's client, through nghttp2_http_on_data_chunk, resets the stream with PROTOCOL_ERROR at the first excess DATA frame and the request errors. The base branch behaves the same way for the client, so this is the sibling site the server-only fix leaves unchanged, not a regression.Verification: pre-existing. A Bun
node:http2client receives a response whose DATA total exceeds itscontent-lengthheader. src/runtime/api/bun/h2/connection.rs:1394-1398 only records the declared length whenself.is_server, sobody_exceeds_content_length()returns false on every client DATA frame. The extra bytes are delivered instead of the stream being reset with PROTOCOL_ERROR.
… and a received field whose value has a control byte is left out
…trictFieldWhitespaceValidation
dylan-conway
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Checked cfdc1035f75 against Node v26.7.0 with a raw peer, comparing the merge base's CI binary with this branch's.
Holds up
node:http: 10,240 cases (every byte in the target, header values, header names and trailers, in 4 leniency modes). 3,874 changed, all from differing with Node to matching it.Bun.serve: 4,608 raw responses are byte-identical to the merge base.node:http2header values: 20,373 cases (server, client, trailers,:pathforms,strictFieldWhitespaceValidationon and off). 6,435 changed to Node's answer.- DATA past
content-length: the handler never gets more than the declared length, and the connection window is given back.
Pushed: 2c8b128
With strictFieldWhitespaceValidation: false, Node and main deliver a :protocol that has a space or tab at an edge. This branch reset the stream. Those 4 cases were the only ones in all the sweeps that went from matching Node to differing. The option already reached the native parser, so the engine now reads it. :protocol matches Node in all 1,536 of its cases.
Still differs from Node (1 and 2 are the same on main)
hostin a request. Node resets the stream withPROTOCOL_ERRORfor an emptyhost, and for a secondhost: equal or different, with or without:authority, or in the trailers after one in the request. Here the handler runs and seeshost: "", or the first of the two. nghttp2 passeshostthroughcheck_pseudo_header, so it has to be non-empty and appear once.:statuson a client. Node refuses a value that is not three digits, is below 100, or is101. Here"2x0"gives'response'with 0,"2000"gives 2000,"+20"gives 20,"1e2"gives'headers'with 100, and"101"gives'headers'with 101.- Resets after the reset. Once a stream is reset for DATA past its
content-length, each later DATA frame on it gets anotherRST_STREAM(STREAM_CLOSED). Four frames giveRST(1) RST(5) RST(5) RST(5), where Node sends one. RFC 9113 §5.1 says to ignore frames on a stream after sendingRST_STREAM. The engine already did this, but the reset now comes in the middle of a body, so frames in flight are the usual case.
Description
- "As in Node" is not exact for
content-length. After theRST_STREAM, Node also sendsGOAWAY(2), which closed an unrelated open stream on the same session in my test. This branch resets only the one stream, which is what §8.1.1 asks for and worth stating. - When the frame arrives split across reads, Node delivers the part that fits the declared length. This branch delivers none of it.
Tests
- Whitespace at an edge of
:statusis described but has no test. I measured it and it holds.
Note
Written by Claude Code on my behalf.
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This is Claude (an AI assistant) replying on Jarred's behalf. @dylan-conway thanks for the sweep and for 2c8b128. I've picked it up, so later pushes from here build on it.
If you push again, a word here helps: I check the remote head before each push, so nothing gets overwritten, but each push restarts CI. |
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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.
Additional findings (outside the current diff — GitHub can't attach inline comments there):
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🟣
src/runtime/api/bun/h2/connection.rs— pre-existing: a node:http2 server still resets a request that carries a regular field with an uppercase or otherwise invalid name, where Node drops the field and serves the request. At connection.rs:1290 is_malformed_field_name marks the whole block malformed for any name, so the stream gets RST_STREAM(PROTOCOL_ERROR) and no 'stream' handler runs. nghttp2 only fails the block for a bad pseudo-header name; a bad regular name is NGHTTP2_ERR_IGN_HTTP_HEADER, and Node's OnInvalidHeader ignores it. Fix: for a regular (non-":") name that fails the check, skip the field withcontinueas the new control-byte branch at connection.rs:1380 does, and keep the malformed verdict only for pseudo-header names.Why this was flagged
A raw HTTP/2 client sends a request block with
:method,:scheme,:path,:authorityand a regular field whose name has an uppercase letter, e.g.X-Trace: 1, to an http2.createServer() server. In finish_header_block the name reaches src/runtime/api/bun/h2/connection.rs:1290, is_malformed_field_name returns true for the uppercase byte, and malformed is set at :1293. The block is then answered at connection.rs:1469-1474 with RST_STREAM(PROTOCOL_ERROR), on_stream_reset and on_stream_rejected, so the handler never sees the request and the rejection counts against maxSessionRejectedStreams. nghttp2's nghttp2_http_on_header returns NGHTTP2_ERR_HTTP_HEADER for an invalid name only when it starts with ':' and NGHTTP2_ERR_IGN_HTTP_HEADER otherwise; Node's Http2Session::OnInvalidHeader returns 0, so Node delivers the request without that field. The base branch behaves the same as this PR here, so this is pre-existing; the PR implements the ignore rule for control bytes in values at connection.rs:1379-1382 but leaves the name counterpart of the same nghttp2 rule as a stream error.Verification: pre-existing. Trigger: a raw HTTP/2 client sends an http2.createServer() server a request block plus one regular field whose name contains a non-uppercase byte outside nghttp2's name charset (e.g.
x@ trace: 1). src/runtime/api/bun/h2/connection.rs line 1290 setsmalformed = trueat 1293 for any such name.malformedthen reaches 1456-1475, so the request never reaches JS. The base commit has the same check, so the base fails the same way.
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This is Claude (an AI assistant) replying on Jarred's behalf. @dylan-conway all four points are in now, at 9b52f0b:
The frame split across reads stays as it is. Node drops the chunk that crosses the length, so what user code sees depends on how TCP cut the frame. The frame's header already says that it goes past the length, so this refuses it there, the same way every time. The description says so. No more pushes are planned from here unless CI or a check finds something. |
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Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.
Additional findings (outside the current diff — GitHub can't attach inline comments there):
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🟣
src/runtime/api/bun/h2/connection.rs— pre-existing: a Bun http2 client still surfaces a PUSH_PROMISE whose:methodisCONNECTas a pushed 'stream', where Node resets the promised stream with PROTOCOL_ERROR and surfaces nothing. The new per-pseudo-header value checks at src/runtime/api/bun/h2/connection.rs:1344 and the CONNECT shape check at connection.rs:1452-1453 accept it when it carries:authorityand no:scheme/:path. Fix: in a PUSH_PROMISE block (push_parent.is_some()), treat:method: CONNECTas malformed alongside the other request pseudo-header rules, so the promised stream gets RST_STREAM(PROTOCOL_ERROR) and no 'stream' event fires.Why this was flagged
A raw HTTP/2 server answers a Bun http2.connect() client's request with a PUSH_PROMISE whose block is
:method: CONNECT,:authority: a(no:scheme, no:path). In finish_header_block the METHOD arm passes pseudo::is_valid_value (connection.rs:1344, CONNECT is a token) and sets saw_connect at connection.rs:1352-1354. The §8.3.1 block at connection.rs:1449-1459 takes the plain-CONNECT branch at :1452-1453, which only requires no :scheme/:path and an :authority, so malformed stays false and sink.on_header/on_headers_complete deliver the push to JS as a 'stream' event with method CONNECT. nghttp2's http_request_on_header rejects CONNECT whenstream->stream_id % 2 == 0("we won't allow CONNECT for push") with NGHTTP2_ERR_HTTP_HEADER, so Node resets the promised stream with PROTOCOL_ERROR and emits no 'stream'. The base branch has the same gap; this PR adds the pseudo-header value rules for PUSH_PROMISE blocks (test 'a promised request with an invalid pseudo-header is refused') but leaves this nghttp2 rule out, so the diff touches the exact arm without closing it.Verification: Trigger: a raw HTTP/2 server answers a Bun http2.connect() client with a PUSH_PROMISE whose block is
:method: CONNECT,:authority: aand no:scheme/:path. The §8.3.1 block takes the plain-CONNECT branch (src/runtime/api/bun/h2/connection.rs:1452-1453), which is false for that shape. Node resets the promised stream with PROTOCOL_ERROR and emits no 'stream'. The base behaves identically.
…e split across reads
What does this PR do?
Hardening for how the
node:httpandnode:http2servers read a request: they now refuse what Node refuses.Bun.serveis not changed.node:http400before any handler runs, and'clientError'getsHPE_INVALID_URL, as in Node. Bun used to run the handler withreq.urldecoded as UTF-8. No parser option relaxes this, in Node or here.400(HPE_INVALID_HEADER_TOKEN), as in Node, unless the parser is lenient (insecureHTTPParser,httpValidation,--insecure-http-parser). Bytes from 0x80 stay valid there and reach the handler as latin1.httpValidationor--insecure-http-parserlost its whole trailer section if one value had a control character.node:http2content-lengthis not delivered. The frame that crosses the length is dropped whole, and the stream is reset withPROTOCOL_ERRORat that frame. It used to be delivered, and the stream was reset only at the end of the request. (the request half of node:http2: hold a response to its content-length #45315)GOAWAYafter theRST_STREAM, which ends the other streams of the session. This resets only the one stream, which is what RFC 9113 §8.1.1 asks for. And if the frame arrives split across reads, Node delivers the part that fits the declared length, where this delivers none of that frame.PROTOCOL_ERRORand no user code runs. The field used to be dropped after the check that it is present, so a handler could see a request without a:pathor a:method. Clients refuse it in:statusand in aPUSH_PROMISEtoo. WithoutstrictFieldWhitespaceValidation,:protocolmay have it, as in Node.:method,:scheme,:pathand:authoritytake the values nghttp2 takes. Forhttpandhttps,:pathhas to start with/, or be*withOPTIONS. Anything else resets the stream withPROTOCOL_ERRORbefore user code runs, in a request and in aPUSH_PROMISE. Ahostthat isn't a valid authority is left out.:status, and aPUSH_PROMISEmay not carry it. Anything else resets the stream withPROTOCOL_ERROR, as in Node.hosthas to be non-empty and appear once, trailers included, as in Node. Otherwise the stream is reset withPROTOCOL_ERROR. (node:http/http2 hardening: enforce h2 request pseudo-headers, never report a failed handler as success, and bound/validate the parser paths (+1 upstream test) #33191 covers this too):statushas to be three digits, from 100 up, and not 101, as in Node. Otherwise the stream is reset."2x0","2000","+20"and"1e2"used to reach'response'or'headers'as a number. (from node:http2: treat a response :status that is not a status code as malformed #43498)RST_STREAM(STREAM_CLOSED). A stream ID that was never used still gets one. (from node:http2: drop DATA and WINDOW_UPDATE on a closed stream like nghttp2 #42467)Behavior change
A client that sends non-ASCII bytes in the URL without escaping them gets
400where Bun 1.4.3 answered. Measured on the wire:curland Go'snet/httpdo that in the query (curl 'http://host/a?q=é'), and Java'sHttpURLConnection, Perl'sHTTP::Tiny, Ruby'sNet::HTTP#getandhttp.request({ path: "/é" })in the path and the query. Node answers all of them with400too. Browsers,fetch,undici,axios,ws,wget, Python'srequestsandjava.net.httpescape these bytes and are not affected.How did you verify your code works?
mainand this branch, on a strict and on a lenient server.Bun.serve: 4,856 raw responses are identical onmainand on this branch. The new checks are behindif constexpr (IsNodeHttp), so its instantiation of the parser doesn't contain them.node-http.test.tsfail onmainand on 1.4.3, and pass on a debug + ASAN build of this branch.node:http2: 14 new tests inh2-conformance.test.ts(six ways of framing the body, with and without TLS, the compatibility API, and the connection's flow-control window) fail onmainand on 1.4.3. An exact-length body, a body withoutcontent-lengthand a short body behave as before.node:http2header values: 5 fields x 255 bytes x 3 positions, withstrictFieldWhitespaceValidationon and off, sent by a raw peer. All 3,825 cells of the pseudo-headers andhostequal Node v26.maindiffers from Node in 2,544 of the sweep's 4,590 cells. Node's owntest-http2-*files pass (261 of 261), and thenode:http2,fetchHTTP/2 and grpc-js tests give the same results as before.