{"id":"CVE-2026-53656","aliases":["GHSA-q78p-hj9h-5466","PYSEC-2026-3465"],"url":"https://o3.security/vulnerability/CVE-2026-53656","summary":"FiftyOne App server uses wildcard CORS (Access-Control-Allow-Origin: *), enabling cross-origin reads of local server data","details":"### Impact\n\nThe FiftyOne App/API server (`fiftyone/server/app.py`) and the `/media` route (`fiftyone/server/routes/media.py`) unconditionally set a permissive CORS header (`Access-Control-Allow-Origin: *`) on their responses. Because the embedded App server runs locally and is unauthenticated, this allows **any website a user visits to make cross-origin requests to that user's running FiftyOne server and read the responses**.\n\nCombined with the unauthenticated `/media` endpoint — which serves files from the local filesystem by path — the wildcard CORS policy turns a local-only file read into a **remotely exploitable, drive-by data exfiltration** vulnerability. A malicious web page can silently issue requests such as `http://localhost:5151/media?filepath=/etc/passwd` and read arbitrary files accessible to the server process (SSH keys, cloud credentials, `.env` files, dataset media, etc.), then exfiltrate them to an attacker-controlled endpoint.\n\nThe victim only needs to have a FiftyOne server running locally and visit a malicious page — no clicks or other interaction are required. Browsers that have shipped Private Network Access / local-network-access protections (e.g. Chromium 142+) mitigate this for some users, but Safari and Firefox do not yet, so the attack remains viable in common configurations.\n\n**Who is impacted:** any user running FiftyOne (the open-source, embedded App server) locally while also browsing the web.\n\n**Not affected:** media stored in cloud buckets, which is served via signed URLs on a separate origin.\n\n### Patches\n\nFixed in **FiftyOne 1.17.0**. The hard-coded `Access-Control-Allow-Origin: *` has been removed and the server now responds **same-origin only by default**, which covers local desktop usage and the supported notebook integrations (each served through a same-origin proxy or iframe).\n\nCross-origin access is now opt-in via a new `allowed_origins` config option (environment variable `FIFTYONE_ALLOWED_ORIGINS`), an explicit comma-separated list of trusted origins, e.g.:\n\n```shell\nexport FIFTYONE_ALLOWED_ORIGINS='https://app.example.com,http://localhost:3000'\n```\n\nThe literal value `*` restores the legacy wildcard behavior for users who explicitly require it and emits a warning.\n\n**Users should upgrade to FiftyOne 1.17.0 or later.**\n\n### Workarounds\n\nIn affected versions there is no configuration flag to disable the wildcard CORS header without upgrading. Until you can upgrade:\n\n- Do not run the FiftyOne App server while browsing untrusted websites.\n- Keep the App server bound to `localhost` (the default) and avoid exposing it on a network interface.\n- Use a browser that enforces Private Network Access protections.\n\n### Resources\n\n- OWASP A01:2025 – Broken Access Control: https://owasp.org/Top10/2025/A01_2025-Broken_Access_Control/","published":"2026-08-21T20:34:55.783Z","modified":"2026-10-21T02:58:30.826100484Z","cvss":{"score":6.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N"},"epss":{"score":0.00093,"percentile":0.00619,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"fiftyone","fixedVersion":"1.17.0"}],"fix":{"url":"https://github.com/voxel51/fiftyone/commit/6c4fa1b27bf53e4ba567742ffd20d033af7b9e64","label":"voxel51/fiftyone@6c4fa1b"},"references":[{"type":"WEB","url":"https://github.com/voxel51/fiftyone/releases/tag/v1.17.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53656.json"},{"type":"ADVISORY","url":"https://github.com/voxel51/fiftyone/security/advisories/GHSA-q78p-hj9h-5466"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53656"},{"type":"FIX","url":"https://github.com/voxel51/fiftyone/commit/6c4fa1b27bf53e4ba567742ffd20d033af7b9e64"},{"type":"FIX","url":"https://github.com/voxel51/fiftyone/commit/7c5b92eec5c7c0210c0c8134351ced77d2800ae0"},{"type":"PACKAGE","url":"https://github.com/voxel51/fiftyone"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:30.826100484Z"}}