{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "source": "REFERENCES"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "eaaaf8494dd5386634ae37d1d122212fdc315be5"
            }
          ],
          "repo": "https://github.com/huggingface/transformers",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "@huntr_ai",
    "cwe_ids": [
      "CWE-22"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9856.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "fixed": "5.10.0"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "A vulnerability in huggingface/transformers versions \u003c=5.8.0.dev0 allows an attacker to perform arbitrary file writes via path traversal. The issue resides in the `save_pretrained()` methods of `PreTrainedTokenizerBase` and `ProcessorMixin`, where keys from the `chat_template` dictionary are used directly as filenames without proper validation. An attacker can exploit this by publishing a malicious Hugging Face Hub repository with a crafted `tokenizer_config.json` file. When a victim downloads and saves the tokenizer or processor, the attacker-controlled keys can escape the intended save directory, enabling arbitrary file writes with attacker-controlled content. This vulnerability affects multiple processors inheriting from `ProcessorMixin`, including Idefics, Florence, Gemma, Phi, and Qwen-VL.",
  "id": "CVE-2026-9856",
  "modified": "2026-08-04T03:32:27.945349786Z",
  "published": "2026-08-02T15:10:53.809Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://huntr.com/bounties/362824d5-fe18-40e8-a6cf-62277f97a170"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9856.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-9856"
    },
    {
      "type": "FIX",
      "url": "https://github.com/huggingface/transformers/commit/eaaaf8494dd5386634ae37d1d122212fdc315be5"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Path Traversal in huggingface/transformers"
}