SeaweedFS: Filer JWT allowed_prefixes literal prefix match allows cross-tenant access to sibling paths

### 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)

CVSS 3.1

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Severity from

GitHub (reviewed advisory)

Weakness

CWE-863

Also known as

BIT-seaweedfs-2026-72921, CVE-2026-72921, GO-2026-6361

• github.com/seaweedfs/seaweedfs/security/advisories/GHSA-gv5w-hfx8-8cwq
• nvd.nist.gov/vuln/detail/CVE-2026-72921
• github.com/seaweedfs/seaweedfs/pull/9439
• github.com/seaweedfs/seaweedfs/commit/05ed5c9ae8a2a45101b52b61d02f170d20d587ff
• github.com/seaweedfs/seaweedfs
• github.com/seaweedfs/seaweedfs/releases/tag/4.24