GitHub namespace permissions are case-sensitive but GitHub usernames/orgs are case-insensitive

[zzstoatzz]

Describe the bug
When authenticating via GitHub OIDC, the registry creates permission patterns using the exact casing from the repository_owner claim (e.g., io.github.PrefectHQ/*). When attempting to publish a server with a lowercase namespace (e.g., io.github.prefecthq/prefect-mcp-server), the publish fails with a 403 error because the permission check at internal/auth/jwt.go:163 uses case-sensitive string matching.

Since GitHub usernames and organization names are case-insensitive, this creates an inconsistency where the registry treats them as case-sensitive.

To Reproduce

1. Authenticate via GitHub OIDC from a repository owned by an organization with capital letters (e.g., PrefectHQ)
2. Create a server.json with a lowercase namespace: io.github.prefecthq/my-server
3. Attempt to publish using mcp-publisher publish
4. Receive 403 error: "You have permission to publish: io.github.PrefectHQ/*. Attempting to publish: io.github.prefecthq/my-server"

Expected behavior
Since GitHub usernames/orgs are case-insensitive, the registry should either:

• Normalize GitHub namespaces to lowercase when creating permissions
• Use case-insensitive matching for io.github.* namespaces
• Accept the server name with either casing

Logs

Publishing to https://registry.modelcontextprotocol.io...
Error: publish failed: server returned status 403: {"title":"Forbidden","status":403,"detail":"You do not have permission to publish this server. You have permission to publish: io.github.PrefectHQ/*. Attempting to publish: io.github.prefecthq/prefect-mcp-server"}

Additional context
The issue occurs in the isResourceMatch function at internal/auth/jwt.go:163 which uses case-sensitive strings.HasPrefix. The permission is created at internal/api/handlers/v0/auth/github_oidc.go:292 using the exact repository_owner value from the OIDC token.

[zzstoatzz]

example

[Avish34]

@tadasant / @domdomegg Should I pick this up?

[domdomegg]

Hmm, I feel a bit icky having to implement this. Is there a strong reason you want your GitHub username and MCP registry namespace to have different casing?

Normalize GitHub namespaces to lowercase when creating permissions
Use case-insensitive matching for io.github.* namespaces
Accept the server name with either casing

If we do do this, accepting the server name with either casing is likely the best of the options: otherwise publishers likely to get confused why they have to use lowercase.

Also curious what Tadas thinks before jumping into this.

[tadasant]

+1 to Adam's question:

Is there a strong reason you want your GitHub username and MCP registry namespace to have different casing?

I don't feel super strongly either way, but in the name of simplicity my default would be to just users should use the same casing. Maybe our error messaging could be more elegant (e.g. display a hint that it failed because your casing does not match, in the case that it matches except for the casing).

If there's a practical reason to allow this though, I agree that accepting the server name with either casing is the best of the options (but it should be immutable for that server thereafter, and cannot collide with matching names of different cases).

[Priyadarshiswain]

Adding another reproducible case, this time using interactive GitHub authentication with mcp-publisher 1.8.0.

• GitHub username: Priyadarshiswain
• Published package: sanjaya-mcp@0.1.0
• Published npm mcpName: io.github.priyadarshiswain/sanjaya
• server.json uses the same lowercase name
• mcp-publisher validate server.json succeeds
• Publishing returns 403 because permission is granted for io.github.Priyadarshiswain/*

The practical problem is that the casing mismatch may be discovered only after the npm version containing mcpName is immutable. Correcting it now requires publishing a new package version even though GitHub ownership is unambiguous.

If case-insensitive matching is not adopted, could mcp-publisher init, validate, or the documentation warn that the GitHub namespace must match the account’s canonical casing before npm publication?