ubuntu-cve-2026-40611
Vulnerability from osv_ubuntu
Published
2026-04-21 18:16
Modified
2026-06-30 16:20
Summary
Details

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.

Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-xenolf-lego-dev",
            "binary_version": "0.3.1-5"
          },
          {
            "binary_name": "lego",
            "binary_version": "0.3.1-5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "golang-github-xenolf-lego",
        "purl": "pkg:deb/ubuntu/golang-github-xenolf-lego@0.3.1-5?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.3.1-5"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-xenolf-lego-dev",
            "binary_version": "3.2.0-1"
          },
          {
            "binary_name": "lego",
            "binary_version": "3.2.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "golang-github-xenolf-lego",
        "purl": "pkg:deb/ubuntu/golang-github-xenolf-lego@3.2.0-1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.3.1-5",
        "2.7.2+dfsg-1",
        "3.2.0-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-xenolf-lego-dev",
            "binary_version": "4.1.3-3ubuntu1.22.04.1"
          },
          {
            "binary_name": "lego",
            "binary_version": "4.1.3-3ubuntu1.22.04.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "golang-github-xenolf-lego",
        "purl": "pkg:deb/ubuntu/golang-github-xenolf-lego@4.1.3-3ubuntu1.22.04.1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.2.0-3.1",
        "4.1.3-3ubuntu1",
        "4.1.3-3ubuntu1.22.04.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-xenolf-lego-dev",
            "binary_version": "4.9.1-2ubuntu0.24.04.3+esm2"
          },
          {
            "binary_name": "lego",
            "binary_version": "4.9.1-2ubuntu0.24.04.3+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "golang-github-xenolf-lego",
        "purl": "pkg:deb/ubuntu/golang-github-xenolf-lego@4.9.1-2ubuntu0.24.04.3+esm2?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.9.1-1build1",
        "4.9.1-2",
        "4.9.1-2ubuntu0.24.04.1",
        "4.9.1-2ubuntu0.24.04.2",
        "4.9.1-2ubuntu0.24.04.2+esm1",
        "4.9.1-2ubuntu0.24.04.3",
        "4.9.1-2ubuntu0.24.04.3+esm1",
        "4.9.1-2ubuntu0.24.04.3+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-xenolf-lego-dev",
            "binary_version": "4.9.1-2"
          },
          {
            "binary_name": "lego",
            "binary_version": "4.9.1-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "golang-github-xenolf-lego",
        "purl": "pkg:deb/ubuntu/golang-github-xenolf-lego@4.9.1-2?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.9.1-2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-xenolf-lego-dev",
            "binary_version": "4.9.1-4"
          },
          {
            "binary_name": "lego",
            "binary_version": "4.9.1-4"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "golang-github-xenolf-lego",
        "purl": "pkg:deb/ubuntu/golang-github-xenolf-lego@4.9.1-4?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.9.1-2",
        "4.9.1-3",
        "4.9.1-4"
      ]
    }
  ],
  "aliases": [],
  "details": "Let\u0027s 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.",
  "id": "UBUNTU-CVE-2026-40611",
  "modified": "2026-06-30T16:20:58Z",
  "published": "2026-04-21T18:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-40611"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-40611"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-40611"
  ]
}



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