GHSA-GV5W-HFX8-8CWQ

Vulnerability from github – Published: 2026-09-02 23:42 – Updated: 2026-09-02 23:42
VLAI
Summary
SeaweedFS: Filer JWT allowed_prefixes literal prefix match allows cross-tenant access to sibling paths
Details

Impact

When a filer JWT restricts a token to a set of path prefixes via allowed_prefixes, the authorization check used a literal byte-prefix match (strings.HasPrefix). A token scoped to /tenant1 therefore also authorized requests to sibling paths such as /tenant1234, /tenant1-old, and /tenant1backup.

In a multi-tenant deployment this lets the holder of one tenant's token access another tenant's data. Because allowed_prefixes gates both read and write tokens, the impact covers cross-tenant reads and writes. A valid scoped token is required, so this is an authorization bypass rather than a fully unauthenticated flaw.

Affected component

  • weed/server/filer_server_handlers.go (JWT allowed_prefixes authorization check)

Patches

Fixed in 4.24. The check now matches on /-separated path components after path.Clean normalisation, so /tenant1 authorizes only /tenant1 and its descendants — not /tenant1234 or other sibling paths.

Workarounds

Where feasible, choose prefix names that are not string-prefixes of one another (e.g. keep a trailing separator convention). Upgrade to 4.24.

References

  • Reported by Kadir Arslan (https://github.com/KadirArslan)
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/seaweedfs/seaweedfs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.0-20260512171048-05ed5c9ae8a2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-72921"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-02T23:42:05Z",
    "nvd_published_at": "2026-08-11T15:17:38Z",
    "severity": "HIGH"
  },
  "details": "### Impact\nWhen a filer JWT restricts a token to a set of path prefixes via `allowed_prefixes`, the authorization check used a literal byte-prefix match (`strings.HasPrefix`). A token scoped to `/tenant1` therefore also authorized requests to sibling paths such as `/tenant1234`, `/tenant1-old`, and `/tenant1backup`.\n\nIn a multi-tenant deployment this lets the holder of one tenant\u0027s token access another tenant\u0027s data. Because `allowed_prefixes` gates both read and write tokens, the impact covers cross-tenant reads and writes. A valid scoped token is required, so this is an authorization bypass rather than a fully unauthenticated flaw.\n\n### Affected component\n- `weed/server/filer_server_handlers.go` (JWT `allowed_prefixes` authorization check)\n\n### Patches\nFixed in **4.24**. The check now matches on `/`-separated path components after `path.Clean` normalisation, so `/tenant1` authorizes only `/tenant1` and its descendants \u2014 not `/tenant1234` or other sibling paths.\n\n### Workarounds\nWhere feasible, choose prefix names that are not string-prefixes of one another (e.g. keep a trailing separator convention). Upgrade to 4.24.\n\n### References\n- Reported by Kadir Arslan (https://github.com/KadirArslan)",
  "id": "GHSA-gv5w-hfx8-8cwq",
  "modified": "2026-09-02T23:42:05Z",
  "published": "2026-09-02T23:42:05Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/seaweedfs/seaweedfs/security/advisories/GHSA-gv5w-hfx8-8cwq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72921"
    },
    {
      "type": "WEB",
      "url": "https://github.com/seaweedfs/seaweedfs/pull/9439"
    },
    {
      "type": "WEB",
      "url": "https://github.com/seaweedfs/seaweedfs/commit/05ed5c9ae8a2a45101b52b61d02f170d20d587ff"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/seaweedfs/seaweedfs"
    },
    {
      "type": "WEB",
      "url": "https://github.com/seaweedfs/seaweedfs/releases/tag/4.24"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "SeaweedFS: Filer JWT allowed_prefixes literal prefix match allows cross-tenant access to sibling paths"
}



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