CVE-2025-3264: Regular Expression Denial of Service (ReDoS) in huggingface/transformers

Severity: medium (CVSS 5.3 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-07-07 · updated 2026-06-17
Weakness: CWE-1333

Description

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically in the `get_imports()` function within `dynamic_module_utils.py`. This vulnerability affects versions 4.49.0 and is fixed in version 4.51.0. The issue arises from a regular expression pattern `\s*try\s*:.*?except.*?:` used to filter out try/except blocks from Python code, which can be exploited to cause excessive CPU consumption through crafted input strings due to catastrophic backtracking. This vulnerability can lead to remote code loading disruption, resource exhaustion in model serving, supply chain attack vectors, and development pipeline disruption.

Affected products

huggingface/transformers: from 4.49.0 before 4.51.0 — fixed in 4.51.0

How to fix

Upgrade to a fixed version: huggingface/transformers 4.51.0. Check the vendor advisory for mitigations.

References

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