CVE-2026-59213: Open WebUI Cross-user Model-list Exposure Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-3wp3-xxj9-5jqq",
  "modified" : "2026-07-24T17:03:21Z",
  "published" : "2026-07-24T17:03:21Z",
  "aliases" : [ "CVE-2026-59213" ],
  "summary" : "Open WebUI: Cross-user model-list exposure via static cache key in get_all_models (aiocache key= vs key_builder= misuse)",
  "details" : "## Summary\n\nThe `get_all_models` handlers in `routers/openai.py` and `routers/ollama.py` intended to cache their **permission-filtered** model lists per user, but the `@cached` decorator was misconfigured: it passed a `key=` lambda instead of `key_builder=`. In aiocache 0.12.3 (the pinned version), `key=` is a **static** cache key — a callable passed there is used as a constant object, not invoked per call. As a result the per-user key was never computed, and all callers collided onto a single shared cache entry within the TTL window. During that window, one user's permission-filtered model list could be served to a different authenticated user, crossing the per-user authorization boundary.\n\n## Impact\n\n- **Boundary crossed:** Confidentiality (cross-user). A caller can receive the model list scoped to a *different* security principal than themselves.\n- A user (or admin, or — depending on endpoint reachability — anonymous caller) who populates the cache causes the next caller within the TTL to receive *that* list rather than their own permission-filtered one.\n- What's disclosed is the set of models another principal can access, including potentially the existence and naming of models restricted from the receiving user.\n- Exposure is **incidental and timing-dependent**, not attacker-controlled: the leaked entry is whatever the most recent caller populated within `MODELS_CACHE_TTL` (default 1 second), and the attacker cannot select the victim or force a target's list into the cache.\n\n## Affected component\n\n- `backend/open_webui/routers/openai.py` — `get_all_models` (~line 488)\n- `backend/open_webui/routers/ollama.py` — `get_all_models` (~line 302)\n\nBoth decorated with `@cached(ttl=MODELS_CACHE_TTL, key=lambda ...)`. No other `@cached(... key=lambda ...)` misuse was found elsewhere in the backend.\n\n## Root cause\n\naiocache 0.12's `@cached` treats `key=` as a static key; the per-call hook is `key_builder=` with signature `key_builder(func, *args, **kwargs)`. Passing a callable to `key=` uses the callable object itself as a constant key, so every invocation resolved to the same entry and the intended per-`user.id` namespacing never occurred.\n\n## Reproduction (default config)\n\n1. On a default deployment, configure at least two users with *different* model-access permissions (e.g. one model restricted to user A).\n2. As user A, request the model list (populates the shared cache entry).\n3. Within `MODELS_CACHE_TTL` (default 1s), as user B, request the model list.\n4. User B receives user A's permission-filtered list, including models B is not permitted to see.\n\n## Remediation\n\nReplace `key=` with `key_builder=` at both call sites and adjust the lambda to take the function as its first argument:\n\n```python\n@cached(\n    ttl=MODELS_CACHE_TTL,\n    key_builder=lambda _func, request, user=None: (\n        f'openai_all_models_{user.id}' if user else 'openai_all_models'\n    ),\n)\n```",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "open-webui"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.6.27"
      }, {
        "fixed" : "0.10.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/security/advisories/GHSA-3wp3-xxj9-5jqq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59213"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/pull/25783"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/commit/0fc630b34b2899599dabffffa012afd47599aa75"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/open-webui/open-webui"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/releases/tag/v0.10.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-524" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-24T17:03:21Z",
    "nvd_published_at" : "2026-07-09T17:17:02Z"
  }
}