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

published 2026-10-26 13 d ago modified 2026-10-28 11 d ago also GHSA-5324-3w58-qpp2 , EUVD-2026-110315

cvss: 6.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 links 4

pypi mem0ai 2.0.18
npm mem0ai 3.1.6

github.com/mem0ai/mem0@71f2ebe commit
github.com/mem0ai/mem0#6892 pull request
github.com/mem0ai/mem0/releases/tag/ts-v3.1.6 release
github.com/mem0ai/mem0/releases/tag/v2.0.18 release

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 12 d ago (2026-10-27)

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.3	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
GitHub	3.1	6.3	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
pypi	mem0ai	<2.0.18	2.0.18
npm	mem0ai	<3.1.6	3.1.6

Affected products

mem0ai mem0

Classification

Weakness

CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
CWE-863 Incorrect Authorization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary