CVE-2026-55640
CriticalCVSS 9.1Exploitation Probability (EPSS)
Low risk40th percentile - higher than 40% of all known CVEs
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.
Risk Assessment
The vulnerability allows unauthorized attackers to manipulate the vector index, potentially leading to data deletion, disruption of semantic search, and data integrity compromise.
Recommendation
It is recommended to immediately upgrade Nextcloud MCP Server to version 0.117.2 or later and configure WEBHOOK_SECRET to enforce authentication.
Related vulnerabilities
- CVE-2026-15340Critical
The lwIP SMTP client does not check the size of inputs, potentially allowing a buffer overflow.
- CVE-2026-108109Critical
PHPNuxBill through 2025.3.20 contains an account takeover vulnerability in the customer password reset flow in system/controllers/forgot.php. An unauthenticated attacker can brute-force the 6-digit otp_code without attempt limits or lockout, then read the newly set password from the HTTP response to hijack the account.
- CVE-2026-108107Critical
PHPNuxBill through 2025.3.20 contains an unauthenticated SQL injection vulnerability in the radius.php FreeRADIUS REST endpoint that interpolates request parameters into whereRaw() queries. Attackers can send crafted username, macAddr or nasid parameters to the accounting or authenticate actions to extract customer records and credentials via time-based blind SQL injection.
- CVE-2026-107806Critical
Nginx UI is a web user interface for the Nginx web server. From 2.3.8 until 2.5.0, an authenticated administrator with an active secure session can submit attacker-controlled portable backup key material and a matching manifest to POST /api/restore. The restore flow trusts the supplied key, decrypts attacker-controlled contents, and replaces the live app.ini, including protected nginx command settings such as TestConfigCmd. Triggering POST /api/nginx/test then executes the restored command in the Nginx UI runtime context, affecting confidentiality, integrity, and availability.
- CVE-2026-105278Critical
The published Docker image for openPDC includes a fixed administrative credential with no forced change on first use. An attacker with network access to the management interface can authenticate using this credential and gain full administrative control of the application.
- CVE-2026-100730Critical
A service console interface on openPDC and openHistorian deserializes a client-supplied data structure. On systems using Windows Authentication, an attacker must already be authenticated to reach this function; on systems without Windows Authentication, this is reachable by an unauthenticated network attacker. This allows an attacker to trigger deserialization of an arbitrary object graph, which could allow remote code execution under the privileges of the affected service account.
- CVE-2026-86405Critical
Improper verification of cryptographic signature vulnerability in Sipay Electronic Money and Payment Services Inc. PrestaShop Virtual POS Module allows Signature Spoofing by Improper Validation. This issue affects PrestaShop Virtual POS Module: from 26.8.1 before 26.9.1.
- CVE-2026-85531Critical
Improper verification of cryptographic signature vulnerability in Sipay Electronic Money and Payment Services Inc. OpenCart Virtual POS Module allows Signature Spoofing by Improper Validation. This issue affects OpenCart Virtual POS Module: from 26.8.2 before 26.9.1.
- CVE-2026-96809Critical
The EduAdmin Booking plugin (eduadmin-booking) by MultiNet Interactive AB contains an SQL Injection vulnerability (improper neutralization of special elements in SQL commands). It allows an attacker to perform blind SQL injection. This issue affects versions from n/a before 6.0.0.
- CVE-2026-96331Critical
The Ajax Search Pro plugin (ajax-search-pro) by wpdreams contains an SQL Injection vulnerability (improper neutralization of special elements in SQL commands). It allows an attacker to perform blind SQL injection. This issue affects versions from n/a through 4.29.1.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

