FazBrowse GitHub Viewer | Trending |
URL:
| Home
Tools: [Download Repo ZIP]   [Original HTTPS Page]

fix: accept wildcard media types in Accept header per RFC 7231 by shivama205 · Pull Request #2152 · modelcontextprotocol/python-sdk · GitHub

/ python-sdk Public

fix: accept wildcard media types in Accept header per RFC 7231 - #2152

Merged
maxisbey merged 2 commits into
modelcontextprotocol:mainfrom
shivama205:fix/accept-header-wildcards
Mar 9, 2026
ConversationCommits (2)ChecksFiles changed
Merged

fix: accept wildcard media types in Accept header per RFC 7231#2152
maxisbey merged 2 commits into
modelcontextprotocol:mainfrom
shivama205:fix/accept-header-wildcards

Conversation

shivama205 commented Feb 27, 2026

Copy link
Copy Markdown
Contributor

Summary

  • Fix _check_accept_headers to accept wildcard media types (*/*, application/*, text/*) in the Accept header, per RFC 7231, section 5.3.2
  • Strip quality value parameters (e.g. ;q=0.8) before matching media types
  • Add comprehensive tests for wildcard acceptance and rejection scenarios

Problem

The server rejected requests with wildcard Accept headers like */* or application/*, returning 406 Not Acceptable. This violated RFC 7231 and broke interoperability with HTTP clients that send Accept: */* by default (e.g. httpx, requests).

Closes #1641

Test plan

  • Wildcard */* accepted for both SSE and JSON-only modes
  • application/* + text/* accepted for SSE mode
  • application/* alone correctly rejected for SSE mode (doesn't cover text/event-stream)
  • Quality parameters (*/*;q=0.8) handled correctly
  • Truly missing Accept header still rejected
  • Incompatible types (text/html) still rejected
  • All 1134 existing tests pass
  • Linting, formatting, and type checks clean

shivama205 commented Feb 27, 2026

Copy link
Copy Markdown
Contributor Author

Hi @Kludex @maxisbey — could you please review this when you get a chance? This fixes #1641 (wildcard Accept header support per RFC 7231). All CI checks are passing. Thanks!

shivama205 commented Feb 28, 2026

Copy link
Copy Markdown
Contributor Author

@felixweinberger @maxisbey could you please review this when you get a chance? Thanks!

shivama205 force-pushed the fix/accept-header-wildcards branch from b5d0136 to 6c49c5f Compare March 4, 2026 18:36

shivama205 commented Mar 4, 2026

Copy link
Copy Markdown
Contributor Author

Bumping this — just rebased onto latest main (clean, no conflicts). This fixes a real interoperability bug: clients like httpx and requests send Accept: */* by default and currently get a 406 Not Acceptable. All CI is passing.

If anyone's on the MCP Discord, would really appreciate a ping to get eyes on this. Happy to make any changes to get it merged. 🙏

maxisbey added bug Something isn't working P2 Moderate issues affecting some users, edge cases, potentially valuable feature improves spec compliance When a change improves ability of SDK users to comply with spec definition labels Mar 5, 2026
maxisbey requested changes Mar 6, 2026
View reviewed changes

maxisbey left a comment

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

Thanks for this — the approach is correct and the test coverage is great. Two small asks before merge (suggestions inline, should be one-click applies).

AI Disclaimer

Comment thread src/mcp/server/streamable_http.py Outdated
Comment thread tests/shared/test_streamable_http.py Outdated
Comment thread tests/shared/test_streamable_http.py Outdated
Comment thread tests/shared/test_streamable_http.py Outdated
Shivam and others added 2 commits March 7, 2026 03:12
fix: accept wildcard media types in Accept header per RFC 7231
6af5bfe 
The server rejected requests with wildcard Accept headers like `*/*`,
`application/*`, or `text/*`, returning 406 Not Acceptable. This violated
RFC 7231, section 5.3.2, which defines wildcard media ranges as valid.

Update `_check_accept_headers` to recognize `*/*` as matching all types,
`application/*` as matching `application/json`, and `text/*` as matching
`text/event-stream`. Also strip quality parameters before matching.

Github-Issue:modelcontextprotocol#1641
Reported-by:rh-fr
fix: address review feedback for accept header parsing
8e2ec6f 
- Normalize media types to lowercase for case-insensitive matching per RFC 7231
- Use exact match instead of startswith to prevent over-matching
- Replace headers.update with headers.pop for cleaner Accept removal in tests
shivama205 force-pushed the fix/accept-header-wildcards branch from d8bd3e4 to 8e2ec6f Compare March 6, 2026 21:44

shivama205 commented Mar 6, 2026

Copy link
Copy Markdown
Contributor Author

Thanks for the thorough review @maxisbey! Applied all your suggestions:

  • Added .lower() for case-insensitive media type matching per RFC 7231
  • Switched from startswith to exact match to prevent over-matching (e.g. application/json-patch+json) — good eye on that one
  • Replaced headers.update({"Accept": None}) with headers.pop("Accept") at all three locations, much cleaner

shivama205 requested a review from maxisbey March 6, 2026 21:57
shivama205 mentioned this pull request Mar 8, 2026
Closed
maxisbey merged commit 51c53f2 into modelcontextprotocol:main Mar 9, 2026
49 of 50 checks passed
maxisbey mentioned this pull request Jun 11, 2026
Merged
9 tasks
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters
Show hidden characters
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

maxisbey maxisbey approved these changes

Assignees

No one assigned

Labels

bug Something isn't working improves spec compliance When a change improves ability of SDK users to comply with spec definition P2 Moderate issues affecting some users, edge cases, potentially valuable feature

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

MCP Server won't work with wildcard in "Accept" header and therefore is non‑compliant with HTTP spec

2 participants

Back | FazBrowse Home | New Git URL