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.
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History
Wed, 22 Apr 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
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| First Time appeared |
Go-acme
Go-acme lego |
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| Vendors & Products |
Go-acme
Go-acme lego |
Wed, 22 Apr 2026 00:00:00 +0000
| Type | Values Removed | Values Added |
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| 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. | |
| Title | Lego: Arbitrary File Write via Path Traversal in Webroot HTTP-01 Provider | |
| Weaknesses | CWE-22 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-04-21T17:58:35.221Z
Updated: 2026-04-21T19:17:54.210Z
Reserved: 2026-04-14T14:07:59.642Z
Link: CVE-2026-40611
Updated: 2026-04-21T18:58:11.603Z
Status : Deferred
Published: 2026-04-21T18:16:52.457
Modified: 2026-04-22T21:17:23.590
Link: CVE-2026-40611
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