ory/fosite · Security
OAuth2 Redirect URL validity does not respect query parameters and character casing for loopback addresses
- GHSA ID
- GHSA-rfq3-w54c-f9q5
- CVE ID
- CVE-2020-15233
- Severity
- medium
- Published
- Updated
- CVSS
- 5.5 · CVSS:3.0/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N/E:P/RL:O/RC:C
- CVSS v3
- 5.5 · CVSS:3.0/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N/E:P/RL:O/RC:C
Description
Impact
fosite#400 (released as v0.30.2) introduced a new feature for handling redirect URLs pointing to loopback interfaces (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
- Registering a client with allowed redirect URL
http://127.0.0.1/callback - Performing OAuth2 flow and requesting redirect URL
http://127.0.0.1/callback?bar=foo - Instead of an error, the browser is redirected to
http://127.0.0.1/callback?bar=foowith a potentially successful OAuth2 response.
as well as the host parameter (as long as the host is a loopback interface):
- Registering a client with allowed redirect URL
https://example.com/callback - Performing OAuth2 flow and requesting redirect URL
http://127.0.0.1/callback - Instead of an error, the browser is redirected to
http://127.0.0.1/callbackwith 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.
CWEs
- CWE-20 · Improper Input Validation
- CWE-601 · URL Redirection to Untrusted Site ('Open Redirect')