CVE-2026-40611

Published: Apr 21, 2026Modified: Jul 15, 2026Deferred

8.8

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploitability: 2.8 / Impact: 5.9

Source: security-advisories@github.com (Secondary)

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.

Related CWEs

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

References (6)

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

Source: security-advisories@github.com

https://access.redhat.com/errata/RHSA-2026:21772

Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

https://access.redhat.com/security/cve/CVE-2026-40611

Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

https://bugzilla.redhat.com/show_bug.cgi?id=2460233

Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

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

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40611.json

Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

Timeline

No history available yet.