CVE-2026-9856

HighCVSS 7.1

Published: 02/08/2026(UTC)Updated: 03/08/2026(UTC)Translated: 02/08/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.30%

22th percentile - higher than 22% of all known CVEs

Summary

Hugging Face Transformers up to version 5.8.0.dev0 has an arbitrary file write vulnerability via path traversal in save_pretrained(). Keys from chat_template are used as filenames without validation.

Risk Assessment

An attacker can publish a malicious repository that, when downloaded and saved by a victim, overwrites arbitrary files on the victim's system.

Recommendation

Upgrade the transformers library to a patched version or restrict trust in downloaded tokenizers.

Other vulnerabilities in Hugging Face Transformers

CVE-2026-75104Medium
Hugging Face Transformers fails to validate shard filenames in checkpoint index files, allowing attackers to read arbitrary files outside the model directory. Malicious index files with parent-directory references or absolute paths can lead to file disclosure and filesystem reconnaissance.

Original NVD description (English source)

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.