CVE-2026-54550: Izpack installer Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-f63g-88cj-hjf9",
  "modified" : "2026-08-26T14:24:40Z",
  "published" : "2026-08-26T14:24:40Z",
  "aliases" : [ "CVE-2026-54550" ],
  "summary" : "IzPack has Path Traversal in UnpackerBase that allows writing files outside the installation directory via malicious pack entries",
  "details" : "### Summary\n\nIzPack's `UnpackerBase.unpack()` resolves pack-file target paths without any\ncanonical-path or directory-containment check. An attacker who distributes a\ntrojanized installer JAR (the format is unsigned) can include pack entries whose\n`targetPath` contains `../` sequences. When a victim runs the installer the\nfile is written to an attacker-chosen location on disk under the victim's\nprivileges — including startup folders, PATH directories, or system locations.\n\n### Details\n\n**Vulnerable method:** `com.izforge.izpack.installer.unpacker.UnpackerBase.unpack()`\n**Source file:** `izpack-installer/src/main/java/com/izforge/izpack/installer/unpacker/UnpackerBase.java`\n**Vulnerable lines (5.2.4):** ~618–627\n\nThe relevant code path is:\n\n```java\nString targetPath = packFile.getTargetPath();             // attacker-controlled\nString path       = IoHelper.translatePath(targetPath, variables); // separator swap ONLY\nFile   target     = new File(path);                       // no canonical check\n// ... mkdirs() then file is written to `target`\n```\n\n`IoHelper.translatePath()` (source: `izpack-util/.../IoHelper.java`) performs\n**only** file-separator character conversion (`'/'` ↔ `File.separatorChar`) and\ncontains no security validation whatsoever. There is no call to\n`getCanonicalPath()`, no `startsWith(installDir)` containment check, and no\nnormalisation of `..` segments.\n\nBecause IzPack installer JARs carry **no digital signature**, an attacker can\nrepack any legitimate installer with malicious `PackFile` entries. The file\nformat is a standard ZIP with serialised resources — no integrity protection.\n\n**Confirmed unpatched in HEAD (fetched from GitHub, 2025):**\n```\ngit show HEAD:izpack-installer/src/main/java/com/izforge/izpack/installer/unpacker/UnpackerBase.java \\\n  | grep -n 'getCanonicalPath\\|startsWith.*install\\|traversal'\n# (no output — fix not present)\n```\n\n### PoC\n\n```bash\n# 1. Clone IzPack source and view the vulnerable code directly\ngit clone --depth=1 --branch izpack-5.2.4 https://github.com/izpack/izpack.git\nsed -n '615,650p' izpack/izpack-installer/src/main/java/com/izforge/izpack/installer/unpacker/UnpackerBase.java\n\n# 2. Compile and run the following Java reproducer (no IzPack classpath needed):\n```\n\n```java\n// TestPathTraversal.java\nimport java.io.*;\n\npublic class TestPathTraversal {\n    // Exact replication of IoHelper.translatePath() — separator swap, no security\n    static String translatePath(String destination) {\n        return destination.replace('/', File.separatorChar);\n    }\n\n    public static void main(String[] args) throws Exception {\n        String installDir   = \"/tmp/izpack_install\";\n        String maliciousPath = installDir + \"/../../../tmp/ESCAPED_FILE\";\n\n        // This is what UnpackerBase does:\n        String path   = translatePath(maliciousPath);\n        File   target = new File(path);           // resolves traversal\n        target.getParentFile().mkdirs();\n        try (FileWriter fw = new FileWriter(target)) {\n            fw.write(\"Written outside install dir via IzPack path traversal\\n\");\n        }\n        System.out.println(\"File written to: \" + target.getCanonicalPath());\n        System.out.println(\"Inside installDir: \" +\n            target.getCanonicalPath().startsWith(new File(installDir).getCanonicalPath()));\n    }\n}\n```\n\n```bash\njavac TestPathTraversal.java && java TestPathTraversal\n# Output: File written to: /tmp/ESCAPED_FILE\n#         Inside installDir: false\n```\n\n### Impact\n\nAny user who runs an IzPack-generated installer is affected. The attacker only\nneeds to distribute a repackaged installer — a common social-engineering vector.\nOn Windows (the primary IzPack platform) the victim typically runs the installer\nas a local administrator, so the attacker can write to `%APPDATA%\\Microsoft\\Windows\\Start Menu\\Programs\\Startup`,\n`%SystemRoot%\\System32`, or any other location reachable by the victim user.\nOn Linux/macOS the same applies for user-writable locations.\n\nNo authentication, no special privileges and no interaction beyond running the\ninstaller are required on the victim side.\n\n### Credits\nThis issue was identified by Michał Majchrowicz, Marcin Wyczechowski, and Paweł Zdunek, members of the AFINE Team.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.codehaus.izpack:izpack-installer"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "5.2.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/izpack/izpack/security/advisories/GHSA-f63g-88cj-hjf9"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/izpack/izpack/pull/1193"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/izpack/izpack/commit/4233ba38d0f1825f9cf3e0204e5261a5498e29d8"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/izpack/izpack/commit/8b7c6792c4fe85e3b1759c106aae39b904848466"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/izpack/izpack"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-26T14:24:40Z",
    "nvd_published_at" : null
  }
}