CVE-2026-9856

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{"affected": [{"affectedData": [{"product": "huggingface/transformers", "vendor": "huggingface", "versions": [{"lessThan": "5.10.0", "status": "affected", "version": "unspecified", "versionType": "custom"}]}], "source": "security@huntr.dev"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Una vulnerabilidad en las versiones menor o igual que 5.8.0.dev0 de huggingface/transformers permite a un atacante realizar escrituras de archivos arbitrarias mediante salto de ruta. El problema reside en los m\u00e9todos \u2019save_pretrained()\u2019 de \u2019PreTrainedTokenizerBase\u2019 y \u2019ProcessorMixin\u2019, donde las claves del diccionario \u2019chat_template\u2019 se utilizan directamente como nombres de archivo sin una validaci\u00f3n adecuada. Un atacante puede explotar esto publicando un repositorio malicioso en Hugging Face Hub con un archivo \u2019tokenizer_config.json\u2019 manipulado. Cuando una v\u00edctima descarga y guarda el tokenizador o procesador, las claves controladas por el atacante pueden escapar del directorio de guardado previsto, permitiendo escrituras de archivos arbitrarias con contenido controlado por el atacante. Esta vulnerabilidad afecta a m\u00faltiples procesadores que heredan de \u2019ProcessorMixin\u2019, incluyendo Idefics, Florence, Gemma, Phi y Qwen-VL."}], "id": "CVE-2026-9856", "lastModified": "2026-10-23T22:10:00.160", "metrics": {"cvssMetricV30": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L", "version": "3.0"}, "exploitabilityScore": 2.8, "impactScore": 4.2, "source": "security@huntr.dev", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-9856", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-08-03T14:57:31.978427Z", "version": "2.0.3"}}]}, "published": "2026-08-02T16:16:25.413", "references": [{"source": "security@huntr.dev", "url": "https://github.com/huggingface/transformers/commit/eaaaf8494dd5386634ae37d1d122212fdc315be5"}, {"source": "security@huntr.dev", "url": "https://huntr.com/bounties/362824d5-fe18-40e8-a6cf-62277f97a170"}], "sourceIdentifier": "security@huntr.dev", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-22"}], "source": "security@huntr.dev", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,5.10.0)"}}], "enrichment": {"confidence": 80.0, "confidence_source": "matching", "scores": [{"score": 80.0, "source": "matching"}]}, "original": {"product": "huggingface/transformers", "source": "cna", "vendor": "huggingface"}, "product": "transformers", "vendor": "huggingface"}], "created": "2026-08-02T19:00:04.298169+00:00", "updated": "2026-08-03T09:15:03.918412+00:00", "vendors": ["huggingface", "huggingface$PRODUCT$transformers"]}