Mem0: Cross-tenant conversation leak via unescaped delimiter collision in session-scope key (_build_session_scope)

Mem0 provides persistent memory infrastructure for AI agents and applications. Prior to Python SDK 2.0.18 and TypeScript SDK 3.1.6, _build_session_scope() in mem0/memory/main.py and Memory.buildSessionScope() in the TypeScript SDK join caller-controlled user_id, agent_id, and run_id values using unescaped & and = delimiters. A caller can embed another scope component in a controlled identifier so that distinct tenant tuples produce the same session_scope key. Memory.add(), AsyncMemory.add(), and the REST POST /memories flow use that key to read and save recent raw messages, allowing cross-tenant conversation disclosure and eviction or interleaving of another tenant's history. This issue is fixed in Python SDK 2.0.18 and TypeScript SDK 3.1.6.

Source published

26 Oct 2026 20:15:01 UTC

Source modified

26 Oct 2026 20:15:01 UTC

Observed here

26 Oct 2026 21:35:30 UTC

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CVSS 3.1 · 6.3 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N