huggingface transformers up to 4.50.x chat.py SETTING_RE redos

Summaryinfo

A vulnerability was found in huggingface transformers up to 4.50.x. It has been classified as problematic. The affected element is an unknown function of the file transformers/commands/chat.py. This manipulation of the argument SETTING_RE causes redos. This vulnerability is registered as CVE-2025-3262. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in huggingface transformers up to 4.50.x. Affected by this vulnerability is an unknown code block of the file transformers/commands/chat.py. The manipulation of the argument SETTING_RE with an unknown input leads to a redos vulnerability. The CWE definition for the vulnerability is CWE-1333. The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles. As an impact it is known to affect availability. The summary by CVE is:

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the huggingface/transformers repository, specifically in version 4.49.0. The vulnerability is due to inefficient regular expression complexity in the `SETTING_RE` variable within the `transformers/commands/chat.py` file. The regex contains repetition groups and non-optimized quantifiers, leading to exponential backtracking when processing 'almost matching' payloads. This can degrade application performance and potentially result in a denial-of-service (DoS) when handling specially crafted input strings. The issue is fixed in version 4.51.0.

The advisory is shared at huntr.com. This vulnerability is known as CVE-2025-3262 since 04/04/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1449.003 for this issue.

Upgrading to version 4.51.0 eliminates this vulnerability. Applying the patch 0720e206c6ba28887e4d60ef60a6a089f6c1cc76 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-20217). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• huggingface

Name

• transformers

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15
• 4.16
• 4.17
• 4.18
• 4.19
• 4.20
• 4.21
• 4.22
• 4.23
• 4.24
• 4.25
• 4.26
• 4.27
• 4.28
• 4.29
• 4.30
• 4.31
• 4.32
• 4.33
• 4.34
• 4.35
• 4.36
• 4.37
• 4.38
• 4.39
• 4.40
• 4.41
• 4.42
• 4.43
• 4.44
• 4.45
• 4.46
• 4.47
• 4.48
• 4.49
• 4.50

License

• open-source

Website

• Product: https://github.com/huggingface/transformers/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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