## Diamond Recursion Scan (traefik) — CLEAN

**Scan date:** 2026-03-29
**Pattern:** Recursive cycle/dependency check without visited set (CWE-407 diamond recursion, O(2^D))

### Files examined

- `pkg/server/router/router.go` — `Manager.traverse()` — **correct implementation**: accepts `visited map[string]bool` and `currentPath map[string]bool`; returns early on `visited[routerName]`. CLEAN.
- `pkg/server/recursion/recursion.go` — `CheckRecursion()` uses context-based tracking. CLEAN.
- `pkg/server/middleware/tcp/middlewares.go` — `checkRecursion()` uses context. CLEAN.

### Verdict: CLEAN — no diamond recursion CWE-407 found in traefik

The `traverse()` function in `pkg/server/router/router.go` explicitly maintains a `visited` map across the recursion. Prior defects (traefik-0001/0002/0003) are O(N) linear slice scans, already documented.
