{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-77937", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-08-21T17:52:36.080Z", "datePublished": "2026-10-20T00:46:14.829Z", "dateUpdated": "2026-10-20T13:48:37.840Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-10-20T00:46:14.829Z"}, "datePublic": "2026-10-18T00:00:00.000Z", "title": "Letta through 0.16.8 Cross-Tenant Impersonation via user_id Header", "descriptions": [{"lang": "en", "value": "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."}], "tags": ["unsupported-when-assigned"], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Authorization Bypass Through User-Controlled Key", "cweId": "CWE-639", "type": "CWE"}]}], "affected": [{"vendor": "letta-ai", "product": "letta", "defaultStatus": "unaffected", "versions": [{"version": "0", "lessThanOrEqual": "0.16.8", "status": "affected", "versionType": "semver"}], "packageURL": "pkg:pypi/letta", "collectionURL": "https://pypi.org", "repo": "https://github.com/letta-ai/letta"}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:letta:letta:*:*:*:*:*:*:*:*", "versionEndIncluding": "0.16.8"}]}]}], "metrics": [{"format": "CVSS", "cvssV4_0": {"version": "4.0", "vectorString": "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", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 8.6, "baseSeverity": "HIGH"}}, {"format": "CVSS", "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH"}}], "references": [{"url": "https://www.lasso.security/vulnerability-database/cve-2026-77937", "tags": ["technical-description", "exploit"], "name": "Lasso.security Advisory"}, {"url": "https://github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/letta/server/rest_api/dependencies.py#L39", "tags": ["technical-description"]}, {"name": "VulnCheck Advisory: Letta through 0.16.8 Cross-Tenant Impersonation via user_id Header", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/letta-through-0.16.8-cross-tenant-impersonation-via-user-id-header"}], "credits": [{"lang": "en", "value": "Noy Pearl", "type": "finder"}, {"lang": "en", "value": "Michael Sromin", "type": "finder"}, {"lang": "en", "value": "Ophir Dror", "type": "finder"}], "x_generator": {"engine": "vulncheck-endgame"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-10-20T13:48:24.242241Z", "id": "CVE-2026-77937", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-20T13:48:37.840Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-77937", "role": "CISA Coordinator", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-20T13:48:24.242241Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-20T13:48:32.739Z"}}], "cna": {"tags": ["unsupported-when-assigned"], "title": "Letta through 0.16.8 Cross-Tenant Impersonation via user_id Header", "credits": [{"lang": "en", "type": "finder", "value": "Noy Pearl"}, {"lang": "en", "type": "finder", "value": "Michael Sromin"}, {"lang": "en", "type": "finder", "value": "Ophir Dror"}], "metrics": [{"format": "CVSS", "cvssV4_0": {"version": "4.0", "baseScore": 8.6, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "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", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH"}}, {"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8.1, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}}], "affected": [{"repo": "https://github.com/letta-ai/letta", "vendor": "letta-ai", "product": "letta", "versions": [{"status": "affected", "version": "0", "versionType": "semver", "lessThanOrEqual": "0.16.8"}], "packageURL": "pkg:pypi/letta", "collectionURL": "https://pypi.org", "defaultStatus": "unaffected"}], "datePublic": "2026-10-18T00:00:00.000Z", "references": [{"url": "https://www.lasso.security/vulnerability-database/cve-2026-77937", "name": "Lasso.security Advisory", "tags": ["technical-description", "exploit"]}, {"url": "https://github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/letta/server/rest_api/dependencies.py#L39", "tags": ["technical-description"]}, {"url": "https://www.vulncheck.com/advisories/letta-through-0.16.8-cross-tenant-impersonation-via-user-id-header", "name": "VulnCheck Advisory: Letta through 0.16.8 Cross-Tenant Impersonation via user_id Header", "tags": ["third-party-advisory"]}], "x_generator": {"engine": "vulncheck-endgame"}, "descriptions": [{"lang": "en", "value": "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."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-639", "description": "Authorization Bypass Through User-Controlled Key"}]}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:letta:letta:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndIncluding": "0.16.8"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-10-20T00:46:14.829Z"}}}, "cveMetadata": {"cveId": "CVE-2026-77937", "state": "PUBLISHED", "dateUpdated": "2026-10-20T13:48:37.840Z", "dateReserved": "2026-08-21T17:52:36.080Z", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "datePublished": "2026-10-20T00:46:14.829Z", "assignerShortName": "VulnCheck"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"collectionURL": "https://pypi.org", "defaultStatus": "unaffected", "packageURL": "pkg:pypi/letta", "product": "letta", "repo": "https://github.com/letta-ai/letta", "vendor": "letta-ai", "versions": [{"lessThanOrEqual": "0.16.8", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "disclosure@vulncheck.com"}], "cveTags": [{"sourceIdentifier": "disclosure@vulncheck.com", "tags": ["unsupported-when-assigned"]}], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-77937", "lastModified": "2026-10-20T20:11:29.833", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "source": "disclosure@vulncheck.com", "type": "Secondary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.6, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "LOW", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "disclosure@vulncheck.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-77937", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-20T13:48:24.242241Z", "version": "2.0.3"}}]}, "published": "2026-10-20T01:17:20.263", "references": [{"source": "disclosure@vulncheck.com", "url": "https://github.com/letta-ai/letta/blob/1131535716e8a31c9a437f8695e25ac98f203a24/letta/server/rest_api/dependencies.py#L39"}, {"source": "disclosure@vulncheck.com", "url": "https://www.lasso.security/vulnerability-database/cve-2026-77937"}, {"source": "disclosure@vulncheck.com", "url": "https://www.vulncheck.com/advisories/letta-through-0.16.8-cross-tenant-impersonation-via-user-id-header"}], "sourceIdentifier": "disclosure@vulncheck.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-639"}], "source": "disclosure@vulncheck.com", "type": "Secondary"}]}

{}