CVE-2026-9856
highpriority · track · 0EPSS 0.005 · 39 %ileEUUSEPSS · scored 2026-10-23
A vulnerability in huggingface/transformers versions <=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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode
ssvc
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weaknesses
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affected products (2)
Products and version ranges known to be affected.
advisories (2)
Vendor and ecosystem advisories describing this.
- GHSA-xrqw-3rrv-vx5wTransformers save_pretrained path traversal allows arbitrary file writes through chat template names2026-08-02ghsa · osvUS
A vulnerability in huggingface/transformers versions < 5.10.0 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.
- PYSEC-2026-3929Transformers save_pretrained path traversal allows arbitrary file writes through chat template names2026-09-10vendor · osvUS
A vulnerability in huggingface/transformers versions < 5.10.0 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.
also known as (5)
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sources
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references (6)
External citations — patches, advisories, analysis.
- https://github.com/huggingface/transformers/commit/eaaaf8494dd5386634ae37d1d122212fdc315be5cnnvd
- https://huntr.com/bounties/362824d5-fe18-40e8-a6cf-62277f97a170cnnvd
- https://github.com/huggingface/transformers/commit/eaaaf8494dd5386634ae37d1d122212fdc315be5enisa_euvd
- https://huntr.com/bounties/362824d5-fe18-40e8-a6cf-62277f97a170enisa_euvd
- https://github.com/huggingface/transformers/commit/eaaaf8494dd5386634ae37d1d122212fdc315be5nvd
- https://huntr.com/bounties/362824d5-fe18-40e8-a6cf-62277f97a170nvd
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