Permissive Cross-domain Policy with Untrusted Domains

Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented `allowed-origins` and `allowed-hosts` flags to align with MCP security guidelines. However, the hardcoded `Access-Control-Allow-Origin: *` header in the SSE initialization handler was inadvertently retained. This vulnerability specifically impacts users connecting via Toolbox using SSE under specification v2024-11-05.Show less

GitLab MCP Server lets an AI agent talk directly to GitLab. Prior to 0.6.0, the HTTP transport in src/transport.ts ships with no authentication layer at all and a wildcard Access-Control-Allow-Origin: * on every response. The structural defect is that the SSE server stands up a stateful, mutation-capable RPC endpoint that is backed by the operator's GITLAB_PERSONAL_ACCESS_TOKEN without any inbound credential check, then advertises itself to every cross-origin browser context via the wildcard CORS header. The httpServer.listen(port) call at line 97 also passes no host argument, so the bind defaults to 0.0.0.0 and exposes the auth-less surface on every interface. This vulnerability is fixed in 0.6.0.Show less

Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, the SSE event server's Access-Control-Allow-Origin response header was hardcoded to the wildcard * regardless of the caller's Origin. Because EventSource does not preflight and does not send cookies, the wildcard is sufficient to let any third-party page the developer visits open a cross-origin EventSource to the SSE port and read the live filename stream from JavaScript. This vulnerability is fixed in 1.17.7.Show less

Cleanuparr is a tool for automating the cleanup of unwanted or blocked files in Sonarr, Radarr, and supported download clients like qBittorrent. Prior to 2.9.10, Cleanuparr's global CORS policy reflects every request Origin and combines it with AllowCredentials(). When DisableAuthForLocalAddresses is enabled, the API also authenticates requests purely by source IP via TrustedNetworkAuthenticationHandler. The combination lets any website that an admin (or any user on a trusted IP) visits read authenticated API responses cross-origin — including the admin's permanent API key. This vulnerability is fixed in 2.9.10.Show less

A flaw has been found in ChatGPTNextWeb NextChat up to 2.16.1. This impacts an unknown function of the file Next.js of the component API Endpoint. Executing a manipulation can lead to permissive cross-domain policy with untrusted domains. The attack may be launched remotely. The exploit has been published and may be used. The project was informed of the problem early through an issue report but has not responded yet.Show less

A security vulnerability has been detected in alexta69 MeTube up to 2026.04.09. This affects the function on_prepare of the file app/main.py of the component CORS Policy. The manipulation leads to permissive cross-domain policy with untrusted domains. The attack is possible to be carried out remotely. The exploit has been disclosed publicly and may be used. Upgrading to version 2026.04.10 is able to mitigate this issue. The identifier of the patch is 0072d3488ae5b8d922d3ee87458d829993742a32. It is recommended to upgrade the affected component.Show less

WWBN AVideo is an open source video platform. In versions 29.0 and below, the `allowOrigin($allowAll=true)` function in `objects/functions.php` reflects any arbitrary `Origin` header back in `Access-Control-Allow-Origin` along with `Access-Control-Allow-Credentials: true`. This function is called by both `plugin/API/get.json.php` and `plugin/API/set.json.php` — the primary API endpoints that handle user data retrieval, authentication, livestream credentials, and state-changing operations. Combined with the application's `SameSite=None` session cookie policy, any website can make credentialed cross-origin requests and read authenticated API responses, enabling theft of user PII, livestream keys, and performing state changes on behalf of the victim. Commit caf705f38eae0ccfac4c3af1587781355d24495e contains a fix.Show less

Glances is an open-source system cross-platform monitoring tool. Prior to version 4.5.4, the Glances web server exposes a REST API (`/api/4/*`) that is accessible without authentication and allows cross-origin requests from any origin due to a permissive CORS policy (`Access-Control-Allow-Origin: *`). This allows a malicious website to read sensitive system information from a running Glances instance in the victim’s browser, leading to cross-origin data exfiltration. While a previous advisory exists for XML-RPC CORS issues, this report demonstrates that the REST API (`/api/4/*`) is also affected and exposes significantly more sensitive data. Version 4.5.4 patches the issue.Show less

A vulnerability was found in ericc-ch copilot-api up to 0.7.0. The impacted element is the function cors of the file src/server.ts of the component Token Endpoint. Performing a manipulation results in permissive cross-domain policy with untrusted domains. It is possible to initiate the attack remotely. The exploit has been made public and could be used.Show less

A security flaw has been discovered in farion1231 cc-switch up to 3.12.3. Affected by this issue is some unknown functionality of the file src-tauri/src/proxy/server.rs of the component ProxyServer. The manipulation results in permissive cross-domain policy with untrusted domains. The attack can be executed remotely. The exploit has been released to the public and may be used for attacks.Show less

Glances is an open-source system cross-platform monitoring tool. Prior to version 4.5.3, the Glances XML-RPC server (activated with glances -s or glances --server) sends Access-Control-Allow-Origin: * on every HTTP response. Because the XML-RPC handler does not validate the Content-Type header, an attacker-controlled webpage can issue a CORS "simple request" (POST with Content-Type: text/plain) containing a valid XML-RPC payload. The browser sends the request without a preflight check, the server processes the XML body and returns the full system monitoring dataset, and the wildcard CORS header lets the attacker's JavaScript read the response. The result is complete exfiltration of hostname, OS version, IP addresses, CPU/memory/disk/network stats, and the full process list including command lines (which often contain tokens, passwords, or internal paths). This issue has been patched in version 4.5.3.Show less

A flaw has been found in vanna-ai vanna up to 2.0.2. Affected by this issue is some unknown functionality of the component FastAPI/Flask Server. Executing a manipulation can lead to permissive cross-domain policy with untrusted domains. The attack can be launched remotely. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.Show less

SiYuan is a personal knowledge management system. Prior to version 3.6.2, a malicious website can achieve Remote Code Execution (RCE) on any desktop running SiYuan by exploiting the permissive CORS policy (Access-Control-Allow-Origin: * + Access-Control-Allow-Private-Network: true) to inject a JavaScript snippet via the API. The injected snippet executes in Electron's Node.js context with full OS access the next time the user opens SiYuan's UI. No user interaction is required beyond visiting the malicious website while SiYuan is running. This issue has been patched in version 3.6.2.Show less

MCP Java SDK is the official Java SDK for Model Context Protocol servers and clients. Prior to versions 0.83.0, 1.0.1, and 1.1.1, there is a hardcoded wildcard CORS vulnerability. This issue has been patched in versions 0.83.0, 1.0.1, and 1.1.1.Show less

Sliver is a command and control framework that uses a custom Wireguard netstack. Prior to version 1.7.4, a single click on a malicious link gives an unauthenticated attacker immediate, silent control over every active C2 session or beacon, capable of exfiltrating all collected target data (e.g. SSH keys, ntds.dit) or destroying the entire compromised infrastructure, entirely through the operator's own browser. This issue has been patched in version 1.7.4.Show less

Nhost is an open source Firebase alternative with GraphQL. Prior to version 1.41.0, The Nhost CLI MCP server, when explicitly configured to listen on a network port, applies no inbound authentication and does not enforce strict CORS. This allows a malicious website visited on the same machine to issue cross-origin requests to the MCP server and invoke privileged tools using the developer's locally configured credentials. This vulnerability requires two explicit, non-default configuration steps to be exploitable. The default nhost mcp start configuration is not affected. This issue has been patched in version 1.41.0.Show less