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NVD description
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.
Priority
LOW
Exploitation
NONE
PoC
NONE
Patch
NONE
Momentum
NONE
#schwachstellen CVE-2026-55640: Nextcloud MCP Server akzeptiert Webhooks ohne Authentifizierung #cve202655640 #nextcloud #nextcloudmcpserver #qdrant https://cybersecurity-news.de/cve-2026-55640-nextcloud-mcp-server-webhook-authentifizierung
Post summary
The note announces CVE‑2026‑55640, indicating that the Nextcloud MCP Server accepts unauthenticated webhooks, but provides no exploit details or mitigation guidance.