GHSA-VW82-7FV8-R6GP严重已审查

Obot has an authorization bypass in /mcp-connect/{id} that allows any authenticated user to use any registered MCP server

OSV 1.4.0 · github-reviewed · 修改于 2026-05-13 23:32

发布时间

2026-05-13 23:32

GitHub 审查时间

2026-05-13 23:32

NVD 发布时间

—

源文件

advisories/github-reviewed/2026/05/GHSA-vw82-7fv8-r6gp/GHSA-vw82-7fv8-r6gp.json

公告说明

Summary

If you have the MCP Server ID, you can connect to the MCP server even if you don't have permissions to the server.

The MCP gateway endpoint /mcp-connect/{mcp_id} does not enforce Access Control Rules (ACRs). Any authenticated Obot user who possesses an MCP Server ID can connect to that server through the gateway — including making tool calls — regardless of whether they are a member of any MCP Registry that grants access to the server.

In practice this means any User can fully use MCP servers that the administrator believed were restricted to specific groups.

Severity

Reporter estimate: Critical.

CVSS 3.1 metric	Value
Attack Vector	Network
Attack Complexity	Low
Privileges Required	Low (authenticated Obot user, any role ≥ Basic)
User Interaction	None
Scope	Changed (Obot authorization bypass enables access to data and operations on an upstream third-party service via Obot's stored OAuth credentials)
Confidentiality	High
Integrity	High (many MCP servers expose write tools — e.g. `updateEmployee`, `submitTimeoffRequest`, ticket creation, file writes)
Availability	None
Vector	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N`
Score	9.3 / Critical

The upstream impact depends on which MCP servers are deployed and what scope their stored credentials hold; the bound is "everything the platform's stored OAuth/API credentials can reach."

Affected Versions

Confirmed on obot v0.21.0.

Vulnerability Details

The intended flow is that a user's authorization is checked during the OAuth process with Obot.

Sign in as the Basic User.
Verify the UI does not list the server in any connector picker (it does not — that path is correctly gated).

Manually craft and call the gateway URL:

POST https://<obot>/mcp-connect/<mcp_server_id>
Authorization: <session cookie or API key>
Content-Type: application/json

{"jsonrpc":"2.0","id":1,"method":"tools/list"}

Observe a successful response listing the server's tools.
Issue an actual tool call:

标识信息

别名 / CVE

无

CWE

CWE-284

软件生态

扩展资料

暂无扩展资料。

CVSS 评分

CVSS_V3

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

原始 OSV JSON

{
  "id": "GHSA-vw82-7fv8-r6gp",
  "aliases": [],
  "details": "## Summary\n\nIf you have the MCP Server ID, you can connect to the MCP server even if you don't have permissions to the server.\n\nThe MCP gateway endpoint `/mcp-connect/{mcp_id}` does not enforce Access Control Rules (ACRs). Any authenticated Obot user who possesses an MCP Server ID can connect to that server through the gateway — including making tool calls — regardless of whether they are a member of any MCP Registry that grants access to the server.\n\nIn practice this means any User can fully use MCP servers that the administrator believed were restricted to specific groups.\n\n## Severity\n\nReporter estimate: **Critical**.\n\n| CVSS 3.1 metric | Value |\n|---|---|\n| Attack Vector | Network |\n| Attack Complexity | Low |\n| Privileges Required | Low (authenticated Obot user, any role ≥ Basic) |\n| User Interaction | None |\n| Scope | Changed (Obot authorization bypass enables access to data and operations on an upstream third-party service via Obot's stored OAuth credentials) |\n| Confidentiality | High |\n| Integrity | High (many MCP servers expose write tools — e.g. `updateEmployee`, `submitTimeoffRequest`, ticket creation, file writes) |\n| Availability | None |\n| **Vector** | `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N` |\n| **Score** | **9.3 / Critical** |\n\nThe upstream impact depends on which MCP servers are deployed and what scope their stored credentials hold; the bound is \"everything the platform's stored OAuth/API credentials can reach.\"\n\n## Affected Versions\n\nConfirmed on `obot v0.21.0`.\n\n## Vulnerability Details\n\nThe intended flow is that a user's authorization is checked during the OAuth process with Obot.\n\n1. The user connects to an MCP URL through Obot.\n2. During the callback, after the user logs into Obot, Obot checks that the user has access to the provided resource (the `/mcp-connect` URL in this case). Obot correctly determines the user's authorization during this flow.\n3. However, another authorization check (the UI authorizer, in this case) was erroneously providing access.\n\n## Reproduction\n\nTested on `obot v0.21.0`.\n\n**Setup:**\n\n1. Configure a multi-user MCP server connected to a sensitive backend — e.g. an HR system, ticketing system, or any service whose stored OAuth token grants broad read/write access. Note its ID.\n4. Create an MCP Registry / Access Control Rule that grants this server **only** to a small group (e.g. two HR employees). Remove the `everyone` group from the relevant rule.\n5. Create or identify a Basic User who is **not** a member of any registry granting access to this server.\n\n**Exploit:**\n\n6. Sign in as the Basic User.\n7. Verify the UI does not list the server in any connector picker (it does not — that path is correctly gated).\n8. Manually craft and call the gateway URL:\n\n   ```\n   POST https://<obot>/mcp-connect/<mcp_server_id>\n   Authorization: <session cookie or API key>\n   Content-Type: application/json\n\n   {\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"tools/list\"}\n   ```\n\n9. Observe a successful response listing the server's tools.\n10. Issue an actual tool call:\n\n   ```json\n   {\"jsonrpc\":\"2.0\",\"id\":2,\"method\":\"tools/call\",\n    \"params\":{\"name\":\"<sensitive_tool>\",\"arguments\":{...}}}\n   ```\n\n11. Observe the call succeeds, returning data scoped only by the **upstream** MCP server's OAuth credentials — not by Obot's ACRs.\n\nThe exploit works equally well via Claude Desktop / Claude Code / any MCP-aware client by configuring the gateway URL as a remote MCP endpoint with the user's API key.",
  "summary": "Obot has an authorization bypass in /mcp-connect/{id} that allows any authenticated user to use any registered MCP server",
  "affected": [
    {
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.21.1"
            }
          ]
        }
      ],
      "package": {
        "name": "github.com/obot-platform/obot",
        "ecosystem": "Go"
      },
      "database_specific": {
        "last_known_affected_version_range": "<= 0.21.0"
      }
    }
  ],
  "modified": "2026-05-13T15:32:11Z",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N"
    }
  ],
  "published": "2026-05-13T15:32:11Z",
  "references": [
    {
      "url": "https://github.com/obot-platform/obot/security/advisories/GHSA-vw82-7fv8-r6gp",
      "type": "WEB"
    },
    {
      "url": "https://github.com/obot-platform/obot",
      "type": "PACKAGE"
    },
    {
      "url": "https://github.com/obot-platform/obot/releases/tag/v0.21.1",
      "type": "WEB"
    }
  ],
  "schema_version": "1.4.0",
  "database_specific": {
    "cwe_ids": [
      "CWE-284"
    ],
    "severity": "CRITICAL",
    "github_reviewed": true,
    "nvd_published_at": null,
    "github_reviewed_at": "2026-05-13T15:32:11Z"
  }
}