Read the docs
TI-2026-40167 Aliases CVE-2026-55640GHSA-8vh3-g2qg-2h2c

Missing authentication in cbcoutinho nextcloud-mcp-server

Priority MEDIUM 47CWE-306Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
None · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-306.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0073 54th percentileScored 2026-11-07
Fix Fixed nextcloud-mcp-server (cbcoutinho): 0.117.2nextcloud-mcp-server (PyPI): 0.117.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
cbcoutinhonextcloud-mcp-serverbefore 0.117.20.117.2Patch availableCNA
—nextcloud-mcp-server (PyPI)before 0.117.20.117.2Patch availableGHSA-8vh3-g2qg-2h2c
  • nextcloud-mcp-server Vendorcbcoutinho Affected before 0.117.2 Fixed in 0.117.2 Patch available CNA
  • nextcloud-mcp-server (PyPI) Vendor— Affected before 0.117.2 Fixed in 0.117.2 Patch available GHSA-8vh3-g2qg-2h2c

Remediation

  • Fix · CNA nextcloud-mcp-server (cbcoutinho) Fixed in 0.117.2
  • Fix · GHSA-8vh3-g2qg-2h2c nextcloud-mcp-server (PyPI) Fixed in 0.117.2 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55640
  2. 2026-10-03 Alias added: GHSA-8vh3-g2qg-2h2c

References

Other 4

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences