CVE-2026-77937

Letta through 0.16.8 contains an authentication bypass vulnerability that allows API callers to impersonate other users by supplying a self-asserted user_id HTTP header. Attackers can set user_id to another tenant's ID, even with LETTA_SERVER_SECURE enabled, to read and modify that user's agents, memory and configuration.

CVSS v3 8.1 HIGH

8.1^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/letta/server/rest_api/dependencies.py#L39
https://www.lasso.security/vulnerability-database/cve-2026-77937
https://www.vulncheck.com/advisories/letta-through-0.16.8-cross-tenant-impersonation-via-user-id-header

Configurations

No configuration.

History

20 Oct 2026, 01:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-20 01:17

Updated : 2026-10-20 20:11

NVD link : CVE-2026-77937

Mitre link : CVE-2026-77937

CVE.ORG link : CVE-2026-77937

JSON object : View

Products Affected

No product.

CWE

CWE-639

Authorization Bypass Through User-Controlled Key

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