← CVE Intelligence

CVE-2026-40611

Lego: Arbitrary File Write via Path Traversal in Webroot HTTP-01 Provider PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
go-acme / legoaffected < 4.34.0

CWE

CWE-22

References

ADP enrichment

CISA-ADP

No English description supplied.

redhat-SADP

A flaw was found in lego, the Let's Encrypt client and ACME library written in Go. A malicious ACME (Automated Certificate Management Environment) server can exploit a path traversal vulnerability in the webroot HTTP-01 challenge provider. By supplying a specially crafted challenge token containing directory traversal sequences, the server can cause lego to write or delete files in arbitrary locations on the system where lego is running, potentially leading to system compromise.