Is CVE-2026-40611 actively exploited?

No active exploitation of CVE-2026-40611 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-40611 be exploited remotely?

Yes. CVE-2026-40611 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-40611?

CVE-2026-40611 has a CVSS score of 8.8 (HIGH).

HOME VULNERABILITIESCVE-2026-40611

HIGH

CVE-2026-40611

CWE-22Published: April 21, 2026· Updated: Apr 22, 2026

8.8

CVSS v3.1

EPSS:0.05%probability of exploitation in 30 daysPercentile:14.0th

Official 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.

NVD Source

Technical Analysis

CVE-2026-40611 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.