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Medium

Hugging Face Transformers library has Regular Expression Denial of Service

  • Disclosed: 14.09.2025
  • Updated: 11.10.2026 15:17

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 software

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PlatformPackageVulnerable versionsFixed in
Python (PyPI) transformers < 4.53.0 4.53.0

References

CVSS score 5.3/10
CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness (CWE)
CWE-1333
Platform
Python (PyPI)
Package
transformers
Disclosed
14.09.2025
Updated
11.10.2026 15:17

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2026-1988 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-rcv9-qm8p-9p6j - CC BY 4.0

Vulnerability history: transformers

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (32) in the archive
Total entries
32
First → latest
05.2023 09.2026
Without a fix
9
Exploited in attacks
0

Severity breakdown

  • High 18
  • Medium 12
  • Low 2

Disclosures per year

Severity:
  1. Hugging Face Transformers downloads custom generation code before trust consent
    High · 7.8 CVE-2026-80047 >= 4.49.0, <= 5.8.1 no fix
  2. Transformers save_pretrained path traversal allows arbitrary file writes through chat template names
    High · 7.1 CVE-2026-9856 < 5.10.0 5.10.0
  3. huggingface/transformers: Arbitrary Code Execution During Model Initialization in the LightGlue Model Loading Path
    High · 8.0 CVE-2026-5241 < 5.5.0 5.5.0
  4. HuggingFace transformers vulnerable to remote code execution
    High · 7.8 CVE-2026-4372 < 5.3.0 5.3.0
  5. Hugging Face Transformers GLM4 Deserialization of Untrusted Data Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of
    High · 7.8 CVE-2025-14930 <= 4.57.1 no fix
  6. Hugging Face Transformers HuBERT convert_config Code Injection Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Hu
    High · 7.8 CVE-2025-14928 <= 4.57.0 no fix
  7. Hugging Face Transformers X-CLIP Checkpoint Conversion Deserialization of Untrusted Data Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on af
    High · 7.8 CVE-2025-14929 <= 5.0.0-rc0 no fix
  8. Hugging Face Transformers SEW convert_config Code Injection Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Huggi
    High · 7.8 CVE-2025-14926 <= 4.57.0 no fix
  9. Hugging Face Transformers SEW-D convert_config Code Injection Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Hug
    High · 7.8 CVE-2025-14927 <= 4.57.0 no fix
  10. Hugging Face Transformers Perceiver Model Deserialization of Untrusted Data Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected instal
    High · 7.8 CVE-2025-14920 <= 4.54.1 no fix
  11. Hugging Face Transformers Transformer-XL Model Deserialization of Untrusted Data Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected i
    High · 7.8 CVE-2025-14921 <= 4.54.1 no fix
  12. Hugging Face Transformers megatron_gpt2 Deserialization of Untrusted Data Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installa
    High · 7.8 CVE-2025-14924 <= 4.55.0 no fix
  13. Hugging Face Transformers library has Regular Expression Denial of Service this entry
    Medium · 5.3 CVE-2025-6051 < 4.53.0 4.53.0
  14. A vulnerability in the `preprocess_string()` function of the `transformers.testing_utils` module in huggingface/transformers version v4.48.3 allows for a Regular Expression Denial of Service (ReDoS) a
    High · 7.5 CVE-2025-2099 < 4.49.0 4.49.0
  15. Deserialization of Untrusted Data in Hugging Face Transformers
    High · 8.8 CVE-2024-11394 < 4.48.0 4.48.0
  16. Deserialization of Untrusted Data in Hugging Face Transformers
    High · 8.8 CVE-2024-11393 < 4.48.0 4.48.0
  17. Deserialization of Untrusted Data in Hugging Face Transformers
    High · 7.5 CVE-2024-11392 < 4.48.0 4.48.0
  18. Deserialization of Untrusted Data in GitHub repository huggingface/transformers prior to 4.36.
    High · 7.8 CVE-2023-7018 < 4.36.0 4.36.0
  19. Deserialization of Untrusted Data in GitHub repository huggingface/transformers prior to 4.36.
    High · 8.8 CVE-2023-6730 < 4.36.0 4.36.0

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