VULNERABILITY INTELLIGENCE
CVE-2026-40611
CVSS score8.8 HIGH
EPSS probability0.42%
CISA KEVNot currently listed
Published2026-04-21
Last modified2026-10-26
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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.
Weakness classification
- security-advisories@github.com: CWE-22
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-22