CVE-2026-34046: Langflow Authenticated Users Can Read, Modify, Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-8c4j-f57c-35cf",
  "modified" : "2026-03-27T21:52:39Z",
  "published" : "2026-03-27T19:36:23Z",
  "aliases" : [ "CVE-2026-34046" ],
  "summary" : "Langflow: Authenticated Users Can Read, Modify, and Delete Any Flow via Missing Ownership Check",
  "details" : "## Vulnerability\n\n### IDOR in `GET/PATCH/DELETE /api/v1/flow/{flow_id}`\n\nThe `_read_flow` helper in `src/backend/base/langflow/api/v1/flows.py` branched on the `AUTO_LOGIN` setting to decide whether to filter by `user_id`. When `AUTO_LOGIN` was `False` (i.e., authentication was enabled), neither branch enforced an ownership check — the query returned any flow matching the given UUID regardless of who owned it.\n\nThis exposed any authenticated user to:\n\n- **Read** any other user's flow, including embedded plaintext API keys\n- **Modify** the logic of another user's AI agents\n- **Delete** flows belonging to other users\n\nThe vulnerability was introduced by the conditional logic that was meant to accommodate public/example flows (those with `user_id = NULL`) under auto-login mode, but inadvertently left the authenticated path without an ownership filter.\n\n---\n\n## Fix (PR #8956)\n\nThe fix removes the `AUTO_LOGIN` conditional entirely and unconditionally scopes the query to the requesting user:\n\n```diff\n-    auth_settings = settings_service.auth_settings\n-    stmt = select(Flow).where(Flow.id == flow_id)\n-    if auth_settings.AUTO_LOGIN:\n-        stmt = stmt.where(\n-            (Flow.user_id == user_id) | (Flow.user_id == None)  # noqa: E711\n-        )\n+    stmt = select(Flow).where(Flow.id == flow_id).where(Flow.user_id == user_id)\n```\n\nAll three operations — read, update, and delete — route through `_read_flow`, so the single change covers the full attack surface. A cross-user isolation test (`test_read_flows_user_isolation`) was added to prevent regression.\n\n---\n\n## Acknowledgements\n\nLangflow thanks the security researcher who responsibly disclosed this vulnerability:\n\n- **[@chximn-dt](https://github.com/chximn-dt)**",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "langflow"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.5.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.5.0"
    }
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "langflow-base"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.5.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.5.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/langflow-ai/langflow/security/advisories/GHSA-8c4j-f57c-35cf"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34046"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/langflow-ai/langflow/pull/8956"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/langflow-ai/langflow"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639", "CWE-862" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-27T19:36:23Z",
    "nvd_published_at" : "2026-03-27T21:17:27Z"
  }
}