CVE-2026-40611

Description

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 write attacker-influenced content to any path writable by the lego process. This vulnerability is fixed in 4.34.0.

CVSS Vector

References

• https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8
• https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8