GHSA-prq8-7wvh-44qh: OAuth: Cross-origin token-request redirects can expose signed request metadata

Cross-origin OAuth token-request redirects can expose signed request metadata Summary 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. Affected - oauth v1.1.5 and prior versions back to and including v0.5.5. - The cross-host token redirect behavior was introduced by https://github.com/ruby-oauth/oauth/commit/d74b767f - The behavior is documented in the v0.5.5 changelog as "Allow redirect to different host but same path". - The vulnerable behavior is in OAuth::Consumer#token_request, which is used by the documented request-token and access-token flows. - The issue is not specific to a Ruby engine or platform. It is caused by the gem's redirect handling and recursive token request behavior. Patched version: oauth v1.1.6. Impact A consumer that calls OAuth::Consumer#get_request_token, OAuth::Consumer#get_access_token, or lower-level token request helpers against an OAuth server whose token endpoint redirect target can be influenced may lose three security properties: 1. Cross-origin signed-request metadata disclosure. The redirected request i