CWE-180: Incorrect Behavior Order: Validate Before Canonicalize

The product validates input before it is canonicalized, which prevents the product from detecting data that becomes invalid after the canonicalization step.

This can be used by an attacker to bypass the validation and launch attacks that expose weaknesses that would otherwise be prevented, such as injection.

Consequences

• Access Control: Bypass Protection Mechanism

How to prevent it

• Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

Recent advisories

• GHSA-8g5g-mxqh-grgj — Vite: `server.fs.deny` bypassed with queries
• GHSA-w74x-v6f9-j3xg — fast-uri vulnerable to URI scheme spoofing via percent-encoded scheme decoding
• GHSA-hxm8-2xgr-2p9m — PyJWT: Non-canonical signature segments enable raw-token revocation bypass
• EEF-CVE-2026-82736 — Ash.Type.CiString validates length and match constraints before case folding, allowing constraint bypass
• GHSA-xpcf-pg52-r92g — Hono has incorrect IP matching in ipRestriction() for IPv4-mapped IPv6 addresses
• GHSA-v2wj-q39q-566r — Vite: `server.fs.deny` bypassed with queries
• GHSA-q4qf-9j86-f5mh — Rack:: Static header_rules bypass via URL-encoded paths
• GHSA-27cr-4p5m-74rj — OpenClaw has a workspace-only sandbox guard mismatch for @-prefixed absolute paths
• GHSA-94vh-gphv-8pm8 — zip Incorrectly Canonicalizes Paths during Archive Extraction Leading to Arbitrary File Write
• GHSA-7jmw-8259-q9jx — Traefik has unexpected behavior with IPv4-mapped IPv6 addresses

All advisories for CWE-180