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MEDIUM6.1

GHSA-rfq3-w54c-f9q5

OAuth2 Redirect URL validity does not respect query parameters and character casing for loopback addresses

Quick fix

GHSA-rfq3-w54c-f9q5 — github.com/ory/fosite: upgrade to the fixed version with the command below.

go get github.com/ory/fosite@v0.34.1

Details

### Impact

[fosite#400](https://github.com/ory/fosite/pull/400) (released as v0.30.2) introduced a new feature for handling redirect URLs pointing to loopback interfaces ([rfc8252#section-7.3](https://tools.ietf.org/html/rfc8252#section-7.3)). As part of that change new behavior was introduced which failed to respect the redirect URL's (only for loopback interfaces!) query parameters

1. Registering a client with allowed redirect URL `http://127.0.0.1/callback` 2. Performing OAuth2 flow and requesting redirect URL `http://127.0.0.1/callback?bar=foo` 3. Instead of an error, the browser is redirected to `http://127.0.0.1/callback?bar=foo` with a potentially successful OAuth2 response.

as well as the host parameter (as long as the host is a loopback interface):

1. Registering a client with allowed redirect URL `https://example.com/callback` 2. Performing OAuth2 flow and requesting redirect URL `http://127.0.0.1/callback` 3. Instead of an error, the browser is redirected to `http://127.0.0.1/callback` with a potentially successful OAuth2 response.

These bugs are only applicable in scenarios where the attacker has control over the loopback interface (`localhost`, `127.0.0.1`, `[::1]`) where the browser performing the OAuth2 flow is running.

Are you affected?

Enter the version of the package you're using.

Affected packages

Go/github.com/ory/fosite
Introduced in: 0.30.3Fixed in: 0.34.1
Fixgo get github.com/ory/fosite@v0.34.1

References