{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-55640", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-06-16T23:52:12.057Z", "datePublished": "2026-08-25T16:03:28.085Z", "dateUpdated": "2026-08-25T19:20:43.689Z"}, "containers": {"cna": {"title": "Nextcloud MCP Server: Unauthenticated `POST /webhooks/nextcloud` allows arbitrary vector data deletion when `WEBHOOK_SECRET` is unset ( default )", "problemTypes": [{"descriptions": [{"cweId": "CWE-306", "lang": "en", "description": "CWE-306: Missing Authentication for Critical Function", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.1, "baseSeverity": "CRITICAL", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H", "version": "3.1"}}], "references": [{"name": "https://github.com/cbcoutinho/nextcloud-mcp-server/security/advisories/GHSA-8vh3-g2qg-2h2c", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/cbcoutinho/nextcloud-mcp-server/security/advisories/GHSA-8vh3-g2qg-2h2c"}, {"name": "https://github.com/cbcoutinho/nextcloud-mcp-server/commit/4fc2b10945108cf1008ec9698291de6706ffcb73", "tags": ["x_refsource_MISC"], "url": "https://github.com/cbcoutinho/nextcloud-mcp-server/commit/4fc2b10945108cf1008ec9698291de6706ffcb73"}, {"name": "https://github.com/cbcoutinho/nextcloud-mcp-server/tree/v0.117.2", "tags": ["x_refsource_MISC"], "url": "https://github.com/cbcoutinho/nextcloud-mcp-server/tree/v0.117.2"}], "affected": [{"vendor": "cbcoutinho", "product": "nextcloud-mcp-server", "versions": [{"version": "< 0.117.2", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-08-25T16:03:28.085Z"}, "descriptions": [{"lang": "en", "value": "Nextcloud MCP Server is a production-ready MCP server that connects AI assistants to a Nextcloud instance. Prior to 0.117.2, the POST /webhooks/nextcloud endpoint in nextcloud_mcp_server/vector/webhook_receiver.py has no authentication by default because WEBHOOK_SECRET defaults to None and startup validation does not require it. When WEBHOOK_SECRET is unset, handle_nextcloud_webhook() accepts unauthenticated requests. The payload[\"user\"][\"uid\"] field parsed in nextcloud_mcp_server/vector/webhook_parser.py is attacker-controlled and is used without an authenticated-session cross-check for Qdrant operations, allowing a network attacker to delete or trigger re-indexing of vector embeddings for any user and to destroy the semantic search index by sending forged deletion events. This issue is fixed in version 0.117.2."}], "source": {"advisory": "GHSA-8vh3-g2qg-2h2c", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-08-25T18:38:39.313226Z", "id": "CVE-2026-55640", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-08-25T19:20:43.689Z"}}]}}

{}

{"affected": [{"affectedData": [{"product": "nextcloud-mcp-server", "vendor": "cbcoutinho", "versions": [{"status": "affected", "version": "< 0.117.2"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Nextcloud MCP Server is a production-ready MCP server that connects AI assistants to a Nextcloud instance. Prior to 0.117.2, the POST /webhooks/nextcloud endpoint in nextcloud_mcp_server/vector/webhook_receiver.py has no authentication by default because WEBHOOK_SECRET defaults to None and startup validation does not require it. When WEBHOOK_SECRET is unset, handle_nextcloud_webhook() accepts unauthenticated requests. The payload[\"user\"][\"uid\"] field parsed in nextcloud_mcp_server/vector/webhook_parser.py is attacker-controlled and is used without an authenticated-session cross-check for Qdrant operations, allowing a network attacker to delete or trigger re-indexing of vector embeddings for any user and to destroy the semantic search index by sending forged deletion events. This issue is fixed in version 0.117.2."}], "id": "CVE-2026-55640", "lastModified": "2026-08-25T16:16:55.810", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.1, "baseSeverity": "CRITICAL", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.2, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-08-25T16:16:55.810", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/cbcoutinho/nextcloud-mcp-server/commit/4fc2b10945108cf1008ec9698291de6706ffcb73"}, {"source": "security-advisories@github.com", "url": "https://github.com/cbcoutinho/nextcloud-mcp-server/security/advisories/GHSA-8vh3-g2qg-2h2c"}, {"source": "security-advisories@github.com", "url": "https://github.com/cbcoutinho/nextcloud-mcp-server/tree/v0.117.2"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-306"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"created": "2026-08-25T18:00:15.519425+00:00", "updated": "2026-08-25T18:45:05.688301+00:00", "vendors": []}