CVE-2026-40611

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.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8
https://access.redhat.com/errata/RHSA-2026:21772
https://access.redhat.com/security/cve/CVE-2026-40611
https://bugzilla.redhat.com/show_bug.cgi?id=2460233
https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40611.json

Configurations

No configuration.

History

No history.

Information

Published : 2026-04-21 18:16

Updated : 2026-07-15 02:21

NVD link : CVE-2026-40611

Mitre link : CVE-2026-40611

CVE.ORG link : CVE-2026-40611

JSON object : View

Products Affected

No product.

CWE

CWE-22

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

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