YunaiV yudao-cloud OAuth2TokenServiceImpl.java getAccessToken improper authentication

A security flaw has been discovered in YunaiV yudao-cloud up to 2026.01. This impacts the function getAccessToken of the file yudao-module-system-biz/src/main/java/io/github/ruoyi/common/oauth2/service/impl/OAuth2TokenServiceImpl.java. Performing a manipulation results in improper authentication. The attack can be initiated remotely. The exploit has been released to the public and may be used for attacks. The vendor explains: "[W]e intentionally retain the existing generic compatibility path that accepts a valid, unexpired stored refresh token when an access-token lookup is unavailable, for integrations such as reports and WebSocket. We are not introducing strict access-token-only verification, new revocation behavior or a separate trusted-entry API. This is a retained compatibility decision, not a claim that this behavior follows the standard OAuth separation or that every identity/revocation scenario has been eliminated."