CVE-2026-40611

HIGH

8.8

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.

CVE Details

CVSS v3.1 Score8.8

SeverityHIGH

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

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionREQUIRED

Published4/21/2026

Last Modified4/22/2026

Sourcenvd

Honeypot Sightings0

Weaknesses (CWE)

CWE-22

References

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

https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8(134c704f-9b21-4f2e-91b3-4a467353bcc0)

IOC Correlations

No correlations recorded

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