CVE-2026-33490 h3: Missing Path Segment Boundary Check in `mount()` Causes Middleware Execution on Unrelated Prefix-Matching Routes

H3 is a minimal HTTP framework. In versions 2.0.0-0 through 2.0.1-rc.16, the mount method in h3 uses a simple startsWith check to determine whether incoming requests fall under a mounted sub-application's path prefix. Because this check does not verify a path segment boundary i.e., that the next...