CVE-2026-107810: Nginx UI Backup Restore Follows Crafted Symlinks Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-p8v3-89rh-jxc7",
  "modified" : "2026-10-09T17:07:05Z",
  "published" : "2026-10-09T17:07:05Z",
  "aliases" : [ "CVE-2026-107810" ],
  "summary" : "Nginx UI: Backup restore follows crafted symlinks into the live Nginx configuration path before restore flags are applied",
  "details" : "### Summary\nAn authenticated user who can create and restore a backup can craft a valid backup archive that causes the restore staging process to write attacker-controlled files into the live Nginx configuration path even when both `restore_nginx` and `restore_nginx_ui` are set to `false`.\n\n### Details\nThe restore flow always extracts the outer archive, verifies the manifest, decrypts `nginx-ui.zip` and `nginx.zip`, and extracts both inner archives before it decides whether `RestoreNginx` or `RestoreNginxUI` should be applied. The zip extractor explicitly allows absolute symlinks when the link target is under `nginx.GetConfPath()` or `nginx.GetModulesPath()`. Later regular-file entries are then created with `os.OpenFile()` on the symlinked path, which follows the symlink and writes into the live path.\n\nRelevant code paths:\n- [internal/backup/restore.go](/home/kali/Desktop/bounty/nginx-ui/internal/backup/restore.go:39)\n- [internal/backup/restore.go](/home/kali/Desktop/bounty/nginx-ui/internal/backup/restore.go:79)\n- [internal/backup/restore.go](/home/kali/Desktop/bounty/nginx-ui/internal/backup/restore.go:204)\n- [internal/backup/restore.go](/home/kali/Desktop/bounty/nginx-ui/internal/backup/restore.go:286)\n- [api/backup/restore.go](/home/kali/Desktop/bounty/nginx-ui/api/backup/restore.go:31)\n- [api/backup/backup.go](/home/kali/Desktop/bounty/nginx-ui/api/backup/backup.go:15)\n\nThis means the restore trust boundary is broken during extraction. A restore request that explicitly opted out of restoring either Nginx or Nginx UI can still modify the live Nginx configuration tree during staging.\n\n### PoC\nI verified this locally in an isolated environment with a temporary package-level harness that exercised the real `Backup()` and `Restore()` implementations.\n\nWhat the executed test did:\n1. Created a temporary `app.ini`, database file, and a temporary live Nginx config directory.\n2. Called the real `Backup()` implementation to obtain a valid backup archive plus AES key/IV.\n3. Extracted the outer backup, decrypted `nginx.zip`, replaced it with a crafted zip containing:\n   - a symlink entry `link -> <live nginx conf dir>`\n   - a later regular file entry `link/poc.conf`\n4. Recomputed `manifest.json` size/hash values for the modified encrypted `nginx.zip` and re-signed `manifest.sig` with the expected signing key derived from the AES key.\n5. Repacked the outer archive and called the real `Restore()` implementation with:\n   - `RestoreNginx: false`\n   - `RestoreNginxUI: false`\n6. Verified that `<live nginx conf dir>/poc.conf` was created anyway.\n\nObserved result from the actual local verification:\n- The crafted restore completed successfully with both restore flags set to `false`.\n- The asserted sink was the existence and content of the live-path file written during restore staging.\n\n### Impact\nAny deployment that allows an authenticated user to create and restore backups is affected. A crafted restore archive can modify the live Nginx configuration path before either restore toggle is honored. This can lead to persistent configuration injection, denial of service on a later reload, or other follow-on impact depending on what files the deployment later consumes from the modified path.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/0xJacky/Nginx-UI"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.9.10-0.20250517140552-daee3ac7ade1"
      }, {
        "fixed" : "1.9.10-0.20260728074146-a467ed652591"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-p8v3-89rh-jxc7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/0xJacky/nginx-ui/commit/a467ed652591fc0cd1b466a1ec751b493faef9f7"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/0xJacky/nginx-ui"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/0xJacky/nginx-ui/releases/tag/v2.5.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-59", "CWE-61" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-09T17:07:05Z",
    "nvd_published_at" : null
  }
}