CVE-2026-120263: When `[oauth2_client].ACCOUNT_LINKING` is set to `auto` (not the default) and registration is enabled, the link-account sign-up form looked up the existing acco

When `[oauth2_client].ACCOUNT_LINKING` is set to `auto` (not the default) and registration is enabled, the link-account sign-up form looked up the existing account to link by the user name or email submitted in the form instead of the identity asserted by the OAuth2 provider. An attacker with an account on a configured OAuth2 provider could submit another user's name, link their external identity to that Gitea account and be signed in as it without its password, including as an administrator. Th