### Impact

An issue in `DigestAuthProvider.verify`:

The `uri` parameter in the client's `Authorization: Digest …` response was not checked against the actual request URL. A captured Digest authentication response could be replayed against any other URL served by the same realm, breaking the per-request-URL binding the Digest scheme assumes.

**Who is affected:** any application using `http4k-security-digest` for HTTP Digest authentication. The bug has been present since `DigestAuthProvider` was introduced (commit `8a52b615b1`, 2021).

### Patches

| Line | Fixed in | Edition |
|------|----------|---------|
| v6.x (Community) | **6.50.0.0** | Community |
| v5.x (LTS) | **5.42.0.0** | Enterprise — contact [enterprise@http4k.org](mailto:enterprise@http4k.org) (if Digest auth is present in your v5.x line) |
| v4.x (LTS) | **4.51.0.0** | Enterprise — contact [enterprise@http4k.org](mailto:enterprise@http4k.org) (if Digest auth is present in your v4.x line) |

The fix:
- Rejects credentials whose `uri` parameter does not match the request URL.

### Workarounds

For deployments that cannot upgrade immediately:
- **URI binding gap:** place Digest auth behind a reverse proxy that pins requests to a single URL.

### References

- Vulnerability first present: [`8a52b615b1`](https://github.com/http4k/http4k/commit/8a52b615b1)
- URI binding fix: [`725f1b9697`](https://github.com/http4k/http4k/commit/725f1b9697)
- Fix release: [v6.50.0.0](https://github.com/http4k/http4k/releases/tag/6.50.0.0)
- Background: [RFC 7616 — HTTP Digest Access Authentication](https://datatracker.ietf.org/doc/html/rfc7616)