CVE-2026-9856Patch

LOWCVSS 7.1 · HIGH

Signal is active with 1 mentions in latest observed window

Immediate actions

Patch affected systems immediately

Recommended action window: Monitor and triage in normal cycle

NVD description

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.

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0.5/ 10 priority

Sources & remediation

Other references

Weakness type (CWE)

CWE-22

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

AVAILABLE

Momentum

STABLE

Threat summary

Patch or workaround signal is available
5 mentions across 3 observed days
Momentum state: stable

What's happening

Patch or workaround mentioned in 3 signals
Technical details provided in 2 signals
Disclosure: 2 classified signals
Peaked 2d ago at 3 mentions (2026-08-02); latest day: 1
5 total mentions across 3 days

Deep dive

Activity timeline5 mentions / 3d

Signal classification2 categories

Patch

360.0%

Disclosure

240.0%

Referenced assets6 URLs

By indicator

Classification over time

Date	Total	Labels

2026-08-02	3	Disclosure2Patch1
2026-08-29	1	Patch1
2026-09-05	1	Patch1

Full discourse5 posts

CVE@CVEnew91d
Disclosure
CVE-2026-9856 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… https://www.cve.org/CVERecord?id=CVE-2026-9856
Post summary
CVE-2026-9856 is a newly disclosed path‑traversal flaw in huggingface/transformers versions <=5.8.0.dev0, allowing arbitrary file writes. No PoC, exploit, or patch details are included in the announcement.
000111.1K
57.9K followersView on X
TheKnight7G@WH173H4758d
Patch
Huggingface's transformers library has a critical CVE-2026-9856 vulnerability. Developers using affected versions need to update urgently to avoid potential exploitation. https://nvd.nist.gov/vuln/detail/CVE-2026-9856
Post summary
The post alerts developers that CVE‑2026‑9856 is a critical flaw and urges them to apply updates to prevent potential exploitation, but it does not provide technical details, exploit code, or evidence of active attacks.
0001038
21 followersView on X
TheKnight7G@WH173H4765d
Patch
The CVE-2026-9856 vulnerability in the huggingface/transformers library exposes many developers to risks. If you're using affected versions, check for updates and patch promptly. https://nvd.nist.gov/vuln/detail/CVE-2026-9856
Post summary
The advisory highlights CVE-2026-9856 in huggingface/transformers and urges users to update and apply patches as soon as possible.
0001048
21 followersView on X
MalwareObserver@MalwareObserver91d
Patch
🐛 VULNERABILITIES CVE Notify: 🚨 [CVE-2026-9856](https://github.com/huggingface/transformers/commit/eaaaf8494dd5386634ae37d1d12221... https://github.com/huggingface/transformers/commit/eaaaf8494dd5386634ae37d1d122212fdc315be5 #CVE #ZeroDay #PatchManagement
Post summary
The post announces CVE‑2026‑9856 and provides GitHub commit links that likely contain the patch, but it offers no exploit details, active exploitation evidence, or technical vulnerability description.
0000042
18 followersView on X
Vulmon Vulnerability Feed@VulmonFeeds91d
Disclosure
CVE-2026-9856 Arbitrary File Write via Path Traversal in Hugging Face Transforme... https://vulmon.com/vulnerabilitydetails?qid=CVE-2026-9856 Customizable Vulnerability Alerts: https://alerts.vulmon.com/?utm_source=twitter&utm_medium=social&utm_campaign=2102281&utm_content=4
Post summary
The tweet announces CVE‑2026‑9856 as an arbitrary file‑write via path traversal in Hugging Face Transformers, linking to Vulmon for details and alerts, but it does not reveal proof of concept, exploit code, or patch information.
00000144
4.1K followersView on X

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What researchers are saying

CVE-2026-9856

TheKnight7G[verified]@WH173H47Patch

The advisory highlights CVE-2026-9856 in huggingface/transformers and urges users to update and apply patches as soon as possible.

MalwareObserver[verified]@MalwareObserverPatch

The post announces CVE‑2026‑9856 and provides GitHub commit links that likely contain the patch, but it offers no exploit details, active exploitation evidence, or technical vulnerability description.

CVE@CVEnewDisclosure

CVE-2026-9856 is a newly disclosed path‑traversal flaw in huggingface/transformers versions <=5.8.0.dev0, allowing arbitrary file writes. No PoC, exploit, or patch details are included in the announcement.

TheKnight7G@WH173H47Patch

The post alerts developers that CVE‑2026‑9856 is a critical flaw and urges them to apply updates to prevent potential exploitation, but it does not provide technical details, exploit code, or evidence of active attacks.

Vulmon Vulnerability Feed@VulmonFeedsDisclosure

The tweet announces CVE‑2026‑9856 as an arbitrary file‑write via path traversal in Hugging Face Transformers, linking to Vulmon for details and alerts, but it does not reveal proof of concept, exploit code, or patch information.