Skip to content

fix(shared): strip HTTP optional whitespace before comparing Mcp-Name (#3763) - #3764

Closed
Pyhroff wants to merge 1 commit into
modelcontextprotocol:mainfrom
Pyhroff:fix/mcp-name-whitespace-normalization
Closed

Pyhroff wants to merge 1 commit into
modelcontextprotocol:mainfrom
Pyhroff:fix/mcp-name-whitespace-normalization

Conversation

@Pyhroff

@Pyhroff Pyhroff commented Oct 26, 2026

Copy link
Copy Markdown

Closes #3763

Description

Per RFC 9110 and SEP-2243 conformance testing, HTTP header field values may carry leading/trailing optional whitespace (OWS: spaces and horizontal tabs). In \classify_inbound_request\ and \decode_header_value, incoming \Mcp-Name\ values with surrounding whitespace were compared verbatim against the body parameter name, causing valid requests to be rejected with JSON-RPC -32020\ (\HEADER_MISMATCH).

Changes

  • Updated \decode_header_value\ in \src/mcp/shared/inbound.py\ to strip surrounding HTTP optional whitespace (\�alue.strip(' \t')) prior to regex matching for the base64 sentinel and verbatim fallback.
  • Added a regression unit test \ est_header_rung_accepts_whitespace_padded_name_header\ in \ ests/shared/test_inbound.py\ ensuring whitespace-padded \Mcp-Name\ values match the decoded body parameter and route successfully.

@github-actions github-actions Bot added the missing-issue-link Auto-closed: PR needs a linked issue assigned to its author (see CONTRIBUTING.md) label Oct 26, 2026
@github-actions

Copy link
Copy Markdown
Contributor

This PR has been closed automatically. This repo only keeps pull requests open when they come from a maintainer, or from a contributor a maintainer has assigned to the linked issue, and you aren't currently assigned to #3763.

If a maintainer assigns you to #3763, this PR reopens on its own and there's nothing more you need to do here. Assignment is a maintainer call based on capacity; comments that only ask to be assigned don't factor in. What does help is engaging on the issue itself by confirming the repro, explaining why it matters for your use case, or describing the approach you'd take.

You're welcome to keep pushing commits here (just avoid force-pushing, since GitHub can't reopen a rewritten branch), but that on its own won't get the PR reviewed or the issue assigned, and realistically most auto-closed PRs stay closed. There's no need to open a new PR either way.

CONTRIBUTING.md has the full reasoning, but in short:

  • We're a small team with very little capacity to review community PRs right now.
  • Many recent PRs are AI-generated with little human review, and reviewing one carefully still costs a maintainer as much time as it ever did. A well-described issue is usually more useful to us than the code.

Maintainers: reopen, remove missing-issue-link, or add bypass-issue-check to override.

@github-actions github-actions Bot closed this Oct 26, 2026
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

missing-issue-link Auto-closed: PR needs a linked issue assigned to its author (see CONTRIBUTING.md)

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2026 Streamable HTTP rejects whitespace-padded Mcp-Name values

1 participant