Arbitrary Remote Code Execution via `_attn_implementation_internal` Config Injection in huggingface/transformers

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Summary

CVECVE-2026-4372
StatePUBLISHED
Assigner@huntr_ai
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-24 14:16:16 UTC
Updated2026-05-26 20:06:20 UTC
DescriptionA critical remote code execution vulnerability exists in all versions of the HuggingFace transformers library prior to version 5.3.0. The vulnerability allows an attacker to craft a malicious `config.json` file containing the `_attn_implementation_internal` field set to an attacker-controlled HuggingFace Hub repository ID. When a victim loads this model using the standard `AutoModelForCausalLM.from_pretrained()` API, the library downloads and executes arbitrary Python code from the attacker's repository with the victim's full OS privileges. This issue arises due to unfiltered deserialization of configuration attributes, insufficient sanitization of internal fields, and unsandboxed execution of downloaded kernels. The vulnerability bypasses the `trust_remote_code` security mechanism, is invisible to the victim, and exploits the standard documented usage pattern, making it particularly severe. Users are advised to upgrade to version 5.3.0 or later to mitigate this issue.

Risk And Classification

Primary CVSS: v3.0 7.8 HIGH from [email protected]

CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS: 0.000320000 probability, percentile 0.099510000 (date 2026-05-31)

Problem Types: CWE-1066 | CWE-1066 CWE-1066 Missing Serialization Control Element

VersionSourceTypeScoreSeverityVector
3.0[email protected]Secondary7.8HIGHCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
3.0CNADECLARED7.8HIGHCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v3.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Huggingface Huggingface/transformers affected unspecified 5.3.0 custom Not specified

References

ReferenceSourceLinkTags
github.com/huggingface/transformers/commit/a7f8e7ff37d87d1a1a0c8cf607971... [email protected] github.com
huntr.com/bounties/1f693a6e-6836-4b8b-a0bd-ca036fba8884 [email protected] huntr.com
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