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CVE-2025-6051: 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: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-09-14 · updated 2026-09-30
• Weakness: CWE-1333

Description

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically within the `normalize_numbers()` method of the `EnglishNormalizer` class. This vulnerability affects versions up to 4.52.4 and is fixed in version 4.53.0. The issue arises from the method's handling of numeric strings, which can be exploited using crafted input strings containing long sequences of digits, leading to excessive CPU consumption. This vulnerability impacts text-to-speech and number normalization tasks, potentially causing service disruption, resource exhaustion, and API vulnerabilities.

Affected products

• huggingface/transformers: 4.52.4

References

• https://github.com/huggingface/transformers/commit/ba8eaba9865618253f997784aa565b96206426f0
• https://huntr.com/bounties/af929523-7b59-418a-bf55-301830b2ac9d

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