TransformersGHSA-4w7r-h757-3r74
Hugging Face Transformers vulnerable to Regular Expression Denial of Service (ReDoS) in the AdamWeightDecay optimizer
Medium5.3CVE-2025-6921 · Published Sep 23, 2025 · updated Sep 10, 2026
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| transformers PyPI | < 4.53.0 | 4.53.0 |
Details and references
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 3.0
- CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Severity from
- GitHub (reviewed advisory)
- Weakness
- CWE-400
- Also known as
- CVE-2025-6921, PYSEC-2026-1980
More Transformers advisories
All Transformers| Date | Advisory | Severity | Fixed in |
|---|---|---|---|
| Sep 142025 | Hugging Face Transformers library has Regular Expression Denial of Service CVE-2025-6051Medium5.3fixed in 4.53.0 | Medium5.3 | 4.53.0 |
| Sep 122025 | Hugging Face Transformers is vulnerable to ReDoS through its MarianTokenizer CVE-2025-6638Medium5.3fixed in 4.53.0 | Medium5.3 | 4.53.0 |
| Aug 62025 | Hugging Face Transformers Regular Expression Denial of Service (ReDoS) vulnerability CVE-2025-5197Medium5.3fixed in 4.53.0 | Medium5.3 | 4.53.0 |
| Jul 112025 | Transformers is vulnerable to ReDoS attack through its DonutProcessor class CVE-2025-3933Medium5.3fixed in 4.52.1 | Medium5.3 | 4.52.1 |
| Jul 72025 | Transformers vulnerable to ReDoS attack through its SETTING_RE variable CVE-2025-3262Medium5.3fixed in 4.51.0 | Medium5.3 | 4.51.0 |
| Jul 72025 | Transformers vulnerable to ReDoS attack through its get_imports() function CVE-2025-3264Medium5.3fixed in 4.51.0 | Medium5.3 | 4.51.0 |