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CVE-2025-6921

Regular Expression Denial of Service (ReDoS) in huggingface/transformers

Published: Sep 23, 2025Updated: Oct 10, 2025 Sources: CVE List NVD GHSA BDUCWE-400
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.5%
Top 63.0%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

The huggingface/transformers library, versions prior to 4.53.0, is vulnerable to Regular Expression Denial of Service (ReDoS) in the AdamWeightDecay optimizer. The vulnerability arises from the _do_use_weight_decay method, which processes user-controlled regular expressions in the include_in_weight_decay and exclude_from_weight_decay lists. Malicious regular expressions can cause catastrophic backtracking during the re.search call, leading to 100% CPU utilization and a denial of service. This issue can be exploited by attackers who can control the patterns in these lists, potentially causing the machine learning task to hang and rendering services unresponsive.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-400

Affected Products

huggingface/transformershuggingface
LibraryLibrary
AI / ML / ml-framework
transformershuggingface
LibraryLibrary
AI / ML / ml-framework
transformersPyPIOSS Libraries
TransformersHugging Face, Inc.
Mixed
AI / ML / ml-framework
huggingfacecommercialAI / MLaka transformers, huggingface/transformers, smolagents
pypipackage-ecosystemOSS Libraries
hugging face, inc.commercialAI / MLaka huggingface, transformers, smolagents

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://huntr.com/bounties/287d15a7-6e7c-45d2-8c05-11e305776f1f
huntr.com
https://github.com/huggingface/transformers/commit/47c34fba5c303576560cb29767efb452ff12b8be
github.com
https://nvd.nist.gov/vuln/detail/CVE-2025-6921
nvd.nist.gov
and 2 more references View all →

Timeline

Published
Sep 23, 2025
Last Updated
Oct 10, 2025

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