CVE-2026-42275: zrok WebDAV Drive Backend Follows Symlinks Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-74m3-9qvm-rp9h",
  "modified" : "2026-05-12T13:29:09Z",
  "published" : "2026-04-25T23:34:35Z",
  "aliases" : [ "CVE-2026-42275" ],
  "summary" : "zrok: WebDAV drive backend follows symlinks outside DriveRoot, enabling host filesystem read/write",
  "details" : "**Summary**\nThe zrok WebDAV drive backend (davServer.Dir) restricts path traversal through lexical normalization but does not prevent symlink following. When a symbolic link inside the shared DriveRoot points to a location outside that root, remote WebDAV consumers can read files and—on shares without OS-level permission restrictions—write or overwrite files anywhere on the host filesystem accessible to the zrok process.\n\n- Attack Vector: Network — exploitation is performed entirely over the WebDAV endpoint; the attacker issues HTTP requests to the public zrok share URL.\n- Attack Complexity: High — a precondition outside the attacker's direct control must hold: a symlink pointing outside DriveRoot must already exist within it (created locally, not via WebDAV).\n- Privileges Required: None — zrok share public --backend-mode drive exposes the WebDAV endpoint with no authentication by default.\n- User Interaction: None — once the symlink precondition is met, exploitation requires no user interaction.\n- Scope: Changed — the vulnerability allows an attacker to escape the WebDAV root (the security boundary) and access the broader host filesystem.\n- Confidentiality Impact: High — arbitrary files readable by the zrok process can be retrieved.\n- Integrity Impact: High — the WebDAV PUT handler opens files with O_RDWR|O_CREATE|O_TRUNC, meaning symlink targets outside DriveRoot can be overwritten (e.g. ~/.ssh/authorized_keys).\n- Availability Impact: None — no direct availability impact.\n\nAffected Components\n\n- drives/davServer/file.go — Dir.OpenFile (line 140), Dir.Stat (line 176), Dir.Mkdir (line 133), Dir.RemoveAll (line 151)\n- endpoints/drive/backend.go — NewBackend (line 51–52)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/openziti/zrok"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.1.11"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/openziti/zrok/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.0.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/openziti/zrok/security/advisories/GHSA-74m3-9qvm-rp9h"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42275"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/openziti/zrok/commit/459bcfc1e121decae1b1d11c37ad94e4ed5bbf2e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/openziti/zrok"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/openziti/zrok/releases/tag/v2.0.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22", "CWE-61" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-25T23:34:35Z",
    "nvd_published_at" : "2026-05-08T04:16:22Z"
  }
}