CVE-2026-61598: djust Client Mass-assignment Of Arbitrary View Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cc7c-9jff-58wj",
  "modified" : "2026-09-16T13:55:48Z",
  "published" : "2026-09-16T13:55:48Z",
  "aliases" : [ "CVE-2026-61598" ],
  "summary" : "djust: Client mass-assignment of arbitrary view attributes via the default dj-model update_model handler",
  "details" : "### Impact\n`djust.mixins.model_binding.ModelBindingMixin` provides a default `update_model` event handler and is part of the **LiveView base MRO**, so every LiveView exposes it. It `setattr`s a view attribute whose **name is client-supplied** (`field`), gated only by: reject `_`-prefixed names; reject a **14-entry denylist** of framework internals (`FORBIDDEN_MODEL_FIELDS`); optional `allowed_model_fields` which **defaults to None = allow all**; and `hasattr` existence.\n\nResult: a client can set **any public, existing view attribute — not just the fields actually bound with `dj-model=` in the rendered template**. The denylist covers framework plumbing but nothing about developer business/authz state, and the allowlist is opt-in (off by default). A developer who binds one `dj-model=\"search\"` input and also keeps `self.account_id` / `self.is_admin` / `self.total_price` as view state does not realize a client can set ALL of them via `{type:event, event:\"update_model\", params:{field, value}}` over the WebSocket. Type coercion matches the target attribute's type (so `\"true\"` -> bool True), aiding the attacker.\n\n**Severity High** for apps that hold authorization/ownership/business state in public view attributes (the normal djust pattern) -> state tampering / IDOR / authz-flag manipulation; Low otherwise. Default-on across every LiveView. For a public (no-login) view an anonymous client can mass-assign; for an authenticated view a logged-in user can tamper their own session's view state (the IDOR/authz vector when downstream handlers act on it without re-authorizing).\n\nReproduced: a view with `account_id/is_admin/total_price` (none bound with dj-model) had all three set via `update_model` calls.\n\n### Patches\nRestrict the default handler to fields actually exposed via `dj-model=`: have the template renderer record the bound-field set per render and reject any `field` outside it (preferred, secure + zero-config); or make `allowed_model_fields` fail-closed (required). Keep `FORBIDDEN_MODEL_FIELDS` only as defense-in-depth. Add a regression that a non-`dj-model` public attribute (e.g. `is_admin`) is rejected while a bound field still updates.\n\n### Workarounds\nSet `allowed_model_fields` explicitly on every view using dj-model (or subclassing LiveView) to the minimal list of bindable fields; do not keep authorization/ownership state in public view attributes that share the view with dj-model bindings.\n\n### References\nReproducer + finding writeup retained privately by the maintainer.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "djust"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.0.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/djust-org/djust/security/advisories/GHSA-cc7c-9jff-58wj"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/djust-org/djust"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/djust-org/djust/releases/tag/v1.0.7"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-915" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-16T13:55:48Z",
    "nvd_published_at" : null
  }
}