CVE-2026-40611
Lego: Arbitrary File Write via Path Traversal in Webroot HTTP-01 Provider
HIGH 8.8EPSS 0.5%
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.
- Affected
- go-acme · lego
- CVSS v3.1 CNA
- 8.8 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - EPSS
- 0.55% chance of exploitation in the next 30 days, 45th percentile
- Published
- 2026-04-21
- Updated
- 2026-07-15