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
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) attack. The regular expression used to process code blocks in docstrings contains nested quantifiers, leading to exponential backtracking when processing input with a large number of newline characters. An attacker can exploit this by providing a specially crafted payload, causing high CPU usage and potential application downtime, effectively resulting in a Denial of Service (DoS) scenario.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | transformers | < 4.49.0 | 4.49.0 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2025-2099
- https://github.com/huggingface/transformers/pull/36648
- https://github.com/huggingface/transformers/commit/8cb522b4190bd556ce51be04942720650b1a3e57
- https://github.com/huggingface/transformers
- https://github.com/pypa/advisory-database/tree/main/vulns/transformers/PYSEC-2025-40.yaml
- https://huntr.com/bounties/97b780f3-ffca-424f-ad5d-0e1c57a5bde4
- https://github.com/advisories/GHSA-qq3j-4f4f-9583
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-1333- Platform
- Python (PyPI)
- Package
transformers- Disclosed
- 19.05.2025
- Updated
- 11.10.2026 12:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-qq3j-4f4f-9583 - CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2025-40 - PyPA Advisory Database; 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.
- 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
- 2023: 3
- 2024: 4
- 2025: 20
- 2026: 5
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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 this entry
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