CVE-2026-54605: OAuth: Cross-origin token-request redirects can expose signed request metadata

When an application uses OAuth::Consumer to request OAuth 1.0 request tokens or access tokens, the token request helper follows 300..399 redirects returned by the OAuth server. In affected versions, OAuth::Consumer#token_request parses the raw Location header, follows the redirect recursively, and can mutate the consumer’s configured site when the redirect points to a different host with the same path.

The result is a cross-origin signed-request disclosure primitive: if an OAuth server token endpoint returns a redirect whose target an attacker controls, the client can re-sign the token request and send OAuth 1.0 request metadata, including the OAuth signature, nonce, timestamp, consumer key, and any request parameters included in the signature base string, to the attacker-controlled host. The same behavior can also be used as an SSRF or confused-deputy primitive because the application server follows the redirect and sends the next request from its own network position.