CVE-2026-55670: ZITADEL Cross-Tenant User Leakage Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6x8v-2fq5-2229",
  "modified" : "2026-06-18T13:07:35Z",
  "published" : "2026-06-18T13:07:34Z",
  "aliases" : [ "CVE-2026-55670" ],
  "summary" : " ZITADEL: Cross-Tenant User Leakage via Recycled Identifiers",
  "details" : "### Summary\n\nA flaw in the user lifecycle enforcement allowed deleted users to retain their original organization/tenant association. Recreating a deleted user under a distinct organization can cause the new user instance to be incorrectly provisioned within the original organization if the previous ID would be used to recreate it.\n\n### Impact\n\nWhen a user is created, the system maps the generated or provided ID to its target organization (`Org A`). When that user is subsequently deleted, a deletion event is appended to the stream, but the historical mapping of the resource owner within the event store's validation layer is not cleared.\n\nIf a new user is later provisioned in a different organization (`Org B`) using that exact same ID, the event store validation logic reads the stream's history, matches it to the original organization, and routes the new user's events to `Org A` instead of `Org B`.\n\nThis issue represents a localized multi-tenancy isolation anomaly rather than an easily exploitable attack vector. Because the new user instance is incorrectly routed and provisioned inside `Org A` instead of `Org B`, an administrator from `Org A` inadvertently gains full access to this new user record.\n\nHowever, there is no technical mechanism for a malicious actor to force, automate, or target this behavior against a specific user or tenant. Because the scenario relies entirely on an accidental sequence of operational events and requires the recycling of a highly specific ID space, the practical security risk is exceptionally low.\n\n### Affected Versions\n\nSystems running one of the following versions are affected:\n\n* **4.x:** `4.0.0` through `4.15.1` (including RC versions)\n* **3.x:** `3.0.0` through `3.4.11` (including RC versions)\n\n### Patches\n\nThe vulnerability has been addressed in the latest releases. The patch resolves the issue by requiring the correct permission in case the verification flag is provided and only allows self-management of the email address, resp. phone number itself.\n\n- **4.x**: Upgrade to $\\ge$[4.15.2](https://github.com/zitadel/zitadel/releases/tag/v4.15.2)\n- **3.x**: Update to $\\ge$[4.15.2](https://github.com/zitadel/zitadel/releases/tag/v4.15.2)\n\n### Workarounds\n\nThe recommended solution is to upgrade to a patched version. \n\n### Questions\n\nIf you have any questions or comments about this advisory, please email us at [security@zitadel.com](mailto:security@zitadel.com)\n\n### Credits\n\nThanks to Charlie Graven from Famedly for reporting this vulnerability.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/zitadel/zitadel"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.80.0-v2.20.0.20260615092437-6082e59d47c1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/zitadel/zitadel/security/advisories/GHSA-6x8v-2fq5-2229"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/zitadel/zitadel/commit/6082e59d47c17a9d54a6b0556b3f31559d7c620a"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/zitadel/zitadel"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/zitadel/zitadel/releases/tag/v4.15.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-284", "CWE-639" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-18T13:07:34Z",
    "nvd_published_at" : null
  }
}