{"id":"CVE-2026-77937","revision":"733fa7a708ca47f19ded70ce08d6a0ba","records":[{"revision":"733fa7a708ca47f19ded70ce08d6a0ba","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-77937","aliases":[],"title":"Letta through 0.16.8 Cross-Tenant Impersonation via user_id Header","description":"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.","state":0,"publishedAt":"2026-10-20T00:46:14.829+00:00","modifiedAt":"2026-10-20T13:48:37.84+00:00","affected":[{"ecosystem":"https://pypi.org","name":"letta","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"letta-ai\",\n                    \"product\": \"letta\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"versions\": [\n                        {\n                            \"version\": \"0\",\n                            \"lessThanOrEqual\": \"0.16.8\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ],\n                    \"packageURL\": \"pkg:pypi/letta\",\n                    \"collectionURL\": \"https://pypi.org\",\n                    \"repo\": \"https://github.com/letta-ai/letta\"\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","score":8.6,"severity":"HIGH"},{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":8.1,"severity":"HIGH"}],"references":["https://www.lasso.security/vulnerability-database/cve-2026-77937","https://github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/letta/server/rest_api/dependencies.py#L39","https://www.vulncheck.com/advisories/letta-through-0.16.8-cross-tenant-impersonation-via-user-id-header"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-77937","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-77937","identifiers":["CVE-2026-77937"]},"retained":false,"historicalAffected":[]}],"coverage":[]}