CVE-2026-55375: canto-saas-api: OAuth credentials exposed in URL query string and exception messages

In affected versions, the OAuth2 token request sends app_id, app_secret, refresh_token and code as URL query parameters of the POST request to https://oauth.<domain>/oauth/api/oauth2/token. Request URLs are commonly recorded in access logs, proxy logs and APM traces, so the application secret and refresh token can be persisted in plain text outside the application’s control.

In addition, when the token request fails, the Guzzle exception message — which contains the full request URI including the credentials — was passed unmodified into the AuthorizationFailedException thrown by OAuth2::obtainAccessToken(). Applications that log exceptions or forward them to error trackers (e.g. Sentry) may therefore have recorded the app secret in their logs.