AI agent vulnerability · Transformers

CVE-2025-6638: Hugging Face Transformers is vulnerable to ReDoS through its MarianTokenizer

mediumCVSS 3.0 5.3GHSA-59p9-h35m-wg4g

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically affecting the MarianTokenizer's removelanguagecode() method. This vulnerability is present in version 4.52.4 and has been fixed in version 4.53.0.

Published Sep 12, 2025 · Updated Sep 15, 2025

Affected packages

transformers

Ecosystem: PyPI
Affected: < 4.53.0
Fixed in: 4.53.0
Check: pip show transformers

Advisory details

From the GitHub Advisory Database (CC BY 4.0).

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically affecting the MarianTokenizer's remove_language_code() method. This vulnerability is present in version 4.52.4 and has been fixed in version 4.53.0. The issue arises from inefficient regex processing, which can be exploited by crafted input strings containing malformed language code patterns, leading to excessive CPU consumption and potential denial of service.

References

How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology

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