CVE-2026-40611HIGH 8.8EPSS p22.4%

CVE-2026-40611CVE-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.

Scoring

CVSS 3.18.8 (HIGH)
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS0.31% probability of exploitation · percentile 22.4% · 2026-06-19T12:03:05Z
Published2026-04-21
Last modified2026-04-22

Underlying weaknesses· 1

CWE-22

References

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

1

TypeTargetConfidenceTier
WeaknessImproper Limitation of a Pathname to a Restricted Directory ('Path Traversal')cwe-220%live

Related by meaning· 6

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Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.