CVE-2026-121938 PUBLISHED

langchain4j-aideepin before 3.31.0 contains an insecure direct object reference vulnerability that allows authenticated users to read other users' character-chat conversations by supplying their character uuid. Attackers can request GET /character/{uuid}, which CharacterService.detail resolves without an ownership check, to obtain victims' questions, AI answers, and attachment and audio URLs.

• hieuPenguinnn finder
• Matthew-james11 remediation developer

• https://github.com/moyangzhan/langchain4j-aideepin/issues/116
• https://hackmd.io/@hieuPenguinnn/langchain4j-aideepin-character-conversation-cross-user-idor
• https://github.com/moyangzhan/langchain4j-aideepin/pull/117
• https://github.com/moyangzhan/langchain4j-aideepin/commit/9b2fee6b66836a0efd5599cfcddd05b80b05ca93
• https://github.com/moyangzhan/langchain4j-aideepin/blob/v3.30.0/server/adi-common/src/main/java/com/moyz/adi/common/service/CharacterService.java#L105-L125
• VulnCheck Advisory: langchain4j-aideepin before 3.31.0 IDOR via GET /character/{uuid}

• Authorization Bypass Through User-Controlled Key CWE