## Summary
- The GitHub token method grants `io.github.<org>/*` publish rights
**only to org Owners** (active `admin` membership — `github_at.go`).
- The DNS/HTTP token methods grant `reversed(domain)/*` for any proven
domain, with no `github.io` special-casing and an empty
`BlockedNamespaces` list.
- `<org>.github.io` is served by GitHub Pages from the
`<org>/<org>.github.io` repository. **Push access to that one
repository** — routinely held by ordinary org members, a much weaker bar
than Owner — is enough to serve a key at
`/.well-known/mcp-registry-auth`, exchange it for a JWT, and publish
under the org's entire `io.github.<org>/*` namespace.
- Reject `github.io` (and subdomains) at the shared
`ValidateDomainAndTimestamp` seam used by both DNS and HTTP exchange;
`io.github.*` publishers already have the GitHub method.
## Impact if unsolved
Any org member with write access to the org's GitHub Pages repo (or an
attacker compromising such a member) can mint MCP packages under the
org's trusted namespace — supply-chain poisoning of every downstream
user who installs `<org>`'s servers from the registry, bypassing the
deliberate Owner-only gate.
## Test plan
- New `TestValidateDomainAndTimestampRejectsGitHubPages`: rejects
`my-org.github.io` (incl. mixed case and subdomains), still allows
lookalikes (`github.io.evil-example.com`,
`my-org.github.io.example.com`) and ordinary domains.
- Full `internal/api/handlers/v0/auth` package passes.
Made with [Cursor](https://cursor.com)
Signed-off-by: SashaMIT <sash@ela.city>
Co-authored-by: Cursor <cursoragent@cursor.com>
## Summary
Follow-up to #1241. Two small tweaks to the `readBody` helper:
- **Rename `readBody` → `readErrorBody`.** The helper is only ever
called on the error path (after a non-2xx status check), where we want a
small string for diagnostics. The generic name made it look reusable on
the success path, where streaming JSON decoding is the right approach.
The new name pins the intended use down.
- **Cap the read with `io.LimitReader` (8 KiB).** Defense in depth —
error diagnostics never need more than a few KB, and we shouldn't buffer
an arbitrarily large body from an upstream just to format an error
message. 8 KiB is well above any realistic GitHub API or JWKS error
response.
No behavior change on the happy path. On the unhappy path, error
messages are now bounded.
## Test plan
- [x] `go build ./...`
- [x] `go test ./internal/api/handlers/v0/auth/...`
🤖 Generated with [Claude Code](https://claude.com/claude-code)
The same pattern for reading an error response body appeared in three
places across the auth handlers:
- `internal/api/handlers/v0/auth/github_at.go` (twice)
- `internal/api/handlers/v0/auth/github_oidc.go` (once)
A shared `readBody` helper function added to `common.go` now handles
this in one place.
The `io` import is removed from both files since it is no longer used
directly there.
---------
Co-authored-by: Radoslav Dimitrov <radoslav@stacklok.com>
## What this does
Fixes an open redirect plus a handful of small, mostly-invisible
hardening changes around it.
## What's in it
- **The fix**: trailing-slash redirects no longer let `//evil.com/`
redirect off-host.
- **SSRF block** on the DNS/HTTP namespace verification — refuses to
dial loopback, RFC1918, link-local, multicast, CGNAT, or
IP-literal/single-label \"domains\".
- **Slow-client guard**: `ReadTimeout` and `IdleTimeout` on the HTTP
server (no `WriteTimeout` — would risk cutting off legitimate
multi-package publishes).
- **Defence-in-depth headers** on the UI (`/`) and 404 responses.
- **5xx responses** stop leaking raw DB error text to clients (logged
server-side instead).
- **Search filter** stops treating `%` and `_` as wildcards.
- **Validators**: PyPI/NuGet identifiers URL-escaped before fetching;
MCPB no longer follows redirects.
- **Misc**: `Version` field bounded to 255 chars; logs quote user input;
`BlockedNamespaces` denylist now catches subdomain claimants.
Each change is its own commit so they can be reviewed (or reverted)
independently.
## Test plan
- [ ] CI green
- [ ] Synthetic publish in staging for each package type (npm, pypi,
nuget, oci, mcpb) — confirms validator changes don't regress
- [ ] Quick browser check of `/` after deploy to confirm UI still loads
with the new CSP
- [ ] `curl https://<host>//evil.com/` — confirm the open redirect is
closed
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
## Summary
DNS auth users have repeatedly hit two failure modes that both produce
the same opaque "Ed25519 signature verification failed" error, making
them indistinguishable to debug. This PR makes both diagnosable
end-to-end without changing the auth protocol or any successful path.
The two recurring failure modes:
1. **Wrong placement** — TXT record put under a selector
(`_mcp-auth.<domain>` or `_mcp-registry.<domain>`) instead of the apex.
DKIM-style intuition, but MCP DNS auth uses SPF-style apex placement.
See #385 (PR #388 fixed the docs but the failure recurred), #1103,
#1126.
2. **Stale apex record** — old TXT record left behind after a key
rotation, silently tried first and rejected.
## Changes
**`internal/api/handlers/v0/auth/dns.go`** — when the apex has no
`v=MCPv1` record, probe `_mcp-auth.<domain>` and
`_mcp-registry.<domain>` in parallel (2s individual timeout). If a
record is found there, return a targeted error pointing the user at the
apex. Costs zero extra DNS work in the success path.
**`internal/api/handlers/v0/auth/common.go`** — when verification fails
against records that *are* present, include short fingerprints of every
key the registry tried (`ed25519:YJLsHFhu`-style 8-char prefix). A new
`ErrSignatureMismatch` sentinel keeps structural errors (wrong signature
size, unsupported algorithm) passing through unchanged via `errors.Is`,
so existing assertions on those messages still hold.
**`docs/modelcontextprotocol-io/authentication.mdx`** — anti-pattern
`<Warning>` callout in the DNS section explicitly warning against
selector placement and stale records.
**Tests** — two new tests:
- `TestDNSAuthHandler_WrongSelectorProbe` — verifies the probe surfaces
records found at `_mcp-auth.` / `_mcp-registry.` and falls through to
the standard error when nothing is found anywhere
- `TestDNSAuthHandler_StaleKeyFingerprintInError` — verifies the
fingerprint hint appears in the failure message for #1126's exact
scenario
One existing test assertion was updated from a generic `"signature
verification failed"` substring to the more specific `"invalid signature
size for ECDSA P-384"` it should always have been asserting; the new
sentinel-based logic surfaces structural errors verbatim.
## Test plan
- [x] `make lint` — clean
- [x] `make test-unit` — all auth tests pass (existing + 2 new)
- [x] Verified existing single-key and multi-key paths preserve their
original (more specific) error messages where they were already specific
- [ ] Reviewer to sanity-check the docs callout renders well in the
Mintlify theme
## Out of scope
The publisher-side preflight DNS check (cross-link in #845) is
intentionally **not** in this PR — that belongs in the broader CLI UX
work tracked by #845.
Refs #845, #385, #1103Fixes#1126
---------
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
## Motivation and Context
See
https://github.com/modelcontextprotocol/registry/issues/482#issuecomment-3436993157
for full details.
This adds ECDSA P-384 (a popular NIST approved curve) in addition to
Ed25519.
## How Has This Been Tested?
I have tested with a local deployment against `mcp.joelverhagen.com`.
Also, I have added significant tests.
## Breaking Changes
None. (hopefully)
## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [x] Documentation update
## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed
## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->
@domdomegg and I spoke a bit about this on Discord:
https://discord.com/channels/1358869848138059966/1369487942862504016/1423710918180606052
---------
Co-authored-by: adam jones <domdomegg+git@gmail.com>
<!-- Provide a brief summary of your changes -->
## Motivation and Context
Currently the `dns` and `http` based auth flows share code well in the
publisher tool. However there is a lot of duplication in the auth
endpoint. This on it's own is not a problem but it does make
enhancements to the proof record (the `v=MCPv1; ...` string) harder to
keep in sync.
This PR adds a `common.go` file to share logic between the two.
This supports work I am prototyping for
https://github.com/modelcontextprotocol/registry/issues/482.
## How Has This Been Tested?
Added new test cases for the permissions. Ran them before and after the
refactoring to ensure no behavior change.
Ran existing UTs.
Ran the integration tests.
Manually exercised the flows locally.
## Breaking Changes
None.
## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [ ] I have added or updated documentation as needed
## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->
