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CVE-2025-6921: The huggingface/transformers library, versions prior to 4.53.0, is vulnerable to Regular Expression …

Occurred
Sep 23, 2025
Published
Sep 23, 2025
Source
NVD CVE

Summary

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.

Tags

  • CVE
  • CVE-2025-6921
  • cvss:HIGH

Classification

Category confidence: 90%
Severity confidence: 85%

Rationale: CVE describes a ReDoS vulnerability in a library causing DoS, not fitting specific AI safety categories like LLM or AGENT.

Classifier: Qwen/Qwen3.5-35B-A3B-FP8

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