CVE-2026-40611

A flaw was found in lego, the Let's Encrypt client and ACME library written in Go. A malicious ACME Automated Certificate Management Environment server can exploit a path traversal vulnerability in the webroot HTTP-01 challenge provider. By supplying a specially crafted challenge token containing...

CVE-2026-40611

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...

CVE-2025-54799 Lego does not enforce HTTPS

Let's Encrypt client and ACME library written in Go Lego. In versions 4.25.1 and below, the github.com/go-acme/lego/v4/acme/api package thus the lego library and the lego cli as well don't enforce HTTPS when talking to CAs as an ACME client. Unlike the http-01 challenge which solves an ACME...