CVE-2026-40611: Improper Limitation of a Pathname to a Restricted Directory

Let's Encrypt client and ACME library written in Go Lego. Prior to 4.34.0, the webroot HTTP-01 challenge provider in lego is vulnerable to arbitrary file write and deletion via path traversal. A malicious ACME server can supply a crafted challenge token containing ../ sequences, causing lego to...