{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/authzed/spicedb"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.34.0"
            },
            {
              "fixed": "1.54.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55866"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T21:42:12Z",
    "nvd_published_at": null,
    "severity": "LOW"
  },
  "details": "### Impact\n Under concurrency, `CheckPermission` and `CheckBulkPermissions` can return `PERMISSIONSHIP_HAS_PERMISSION` for a (resource, permission, subject) whose correct answer is   `PERMISSIONSHIP_CONDITIONAL_PERMISSION`. \n\n You are impacted if **all** of the following hold:\n\n  1. Your schema has a permission combining relations with an intersection or exclusion, where a subject reaches it through a caveated branch and a non-caveated branch. For example:\n\n```zed\n  definition user {}\n\n  caveat some_caveat(somecondition int) { somecondition == 42 }\n\n  definition document {\n    relation reader: user | user with some_caveat\n    relation writer: user\n    relation banned: user\n    permission has_permission = (reader \u0026 writer) - banned\n  }\n```\n\n  2. A subject reaches the permission via the caveated edge:\n\n```\n  document:firstdoc#reader@user:caveatedreader[some_caveat]\n  document:firstdoc#writer@user:caveatedreader\n```\n  3. Your workload issues `LookupResources` with a `context` request parameter, concurrently with `CheckPermission/CheckBulkPermissions` for the same subject/resource, and\n  4. The dispatch result cache is enabled.\n  \nWhen all of the above are true, there is an intermittent window in which:\n\n`CheckPermission(document:firstdoc, has_permission, user:caveatedreader)` \u2192 HAS_PERMISSION (incorrect; should be CONDITIONAL_PERMISSION)\n\n`CheckPermission(document:firstdoc, has_permission, user:caveatedreader, context = {\"somecondition\": 41})` \u2192 HAS_PERMISSION (incorrect; should be NO_PERMISSION)\n\n### Patches\n\nv1.54.0\n\n### Workarounds\nDisable the dispatch result cache (`ClusterDispatchCacheConfig` and `DispatchCacheConfig`)",
  "id": "GHSA-4vrg-r928-h5vv",
  "modified": "2026-06-19T21:42:12Z",
  "published": "2026-06-19T21:42:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/authzed/spicedb/security/advisories/GHSA-4vrg-r928-h5vv"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/authzed/spicedb"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "SpiceDB: Checks involving relations with caveats can result in unconditional permission when conditional permission is expected"
}