CVE-2026-40611
8.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
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 Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| go-acme | lego | < 4.34.0 | affected |
Weaknesses
- CWE-22: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: poc
- Automatable: no
- Technical Impact: total
Additional References
github.com/go-acme/lego: Lego: Arbitrary file write and deletion via path traversal from a malicious ACME server
Additional References
- https://access.redhat.com/security/cve/CVE-2026-40611
- https://bugzilla.redhat.com/show_bug.cgi?id=2460233
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40611.json
- https://access.redhat.com/errata/RHSA-2026:21772
References
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