CVE-2026-29054: traefik CVE-2024-45410 fix bypass: lowercase `Connection` tokens can delete traefik-managed forwarded identity headers (for example, `X-Real-Ip`)

There is a potential vulnerability in Traefik managing the Connection header with X-Forwarded headers.

When Traefik processes HTTP/1.1 requests, the protection put in place to prevent the removal of Traefik-managed X-Forwarded headers (such as X-Real-Ip, X-Forwarded-Host, X-Forwarded-Port, etc.) via the Connection header does not handle case sensitivity correctly. The Connection tokens are compared case-sensitively against the protected header names, but the actual header deletion operates case-insensitively. As a result, a remote unauthenticated client can use lowercase Connection tokens (e.g. Connection: x-real-ip) to bypass the protection and trigger the removal of Traefik-managed forwarded identity headers.

This is a bypass of the fix for CVE-2024-45410.

Depending on the deployment, the impact may be higher if downstream services rely on these headers (such as X-Real-Ip or X-Forwarded-*) for authentication, authorization, routing, or scheme decisions.