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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.231 ·

MCP OAuth callback now redirects to localhost rather than 127.0.0.1

MCP OAuth logins now send you back via localhost, so servers only allowing the IP form will reject you.

You'll notice Improvements
JSON All of v2.1.231
You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.231,
ImprovementsSection of the release
What

When Claude Code logs in to an MCP server over OAuth, the default address it hands the server to send you back to is now http://localhost:<port>/callback instead of http://127.0.0.1:<port>/callback. If a server has the old IP form registered as its only allowed redirect, that login will now be rejected until the localhost form is added.

Details
  • The port is taken from the server's oauth.callbackPort setting, falling back to Claude Code's own MCP OAuth callback port.
  • Configuring an explicit redirectUri for a server still overrides this entirely, and that path logs "(no localhost listener)" since Claude Code is not the one receiving the redirect.
  • This aligns the default with two other places in the same code that already built the localhost form, so all three now agree.
Evidence

/callback

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.231 →

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