GHSA-4w7r-h757-3r74 CVE-2025-6921 PYSEC-2026-1980
Hugging Face Transformers vulnerable to Regular Expression Denial of Service (ReDoS) in the AdamWeightDecay optimizer
- Severity
- 5.3 / 10
- High · CVSS 3.0
- Exploit chance (EPSS)
- 0.51%
- Chance of exploitation in the next 30 days. Higher than 43.59% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-400 Uncontrolled Resource Consumption
- Fix
4.53.0- Upgrade transformers to this version or later
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.
Affected versions
PyPI
| Package | Vulnerable | Fixed in |
|---|---|---|
| transformers | < 4.53.0 |
4.53.0 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
transformers PyPI → 4.53.0
- pip
pip install --upgrade "transformers>=4.53.0"- poetry
poetry add "transformers>=4.53.0"- uv
uv add "transformers>=4.53.0"
Severity breakdown
CVSS 3.0 5.3
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Weakness
CWE-400: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How to prevent it
- Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
- Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Implementation: Ensure that all failures in resource allocation place the system into a safe posture.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-x9r9-c232-4q39 Hugging Face Transformers downloads custom generation code before trust consent | High | Also affects transformers |
| GHSA-xrqw-3rrv-vx5w Transformers save_pretrained path traversal allows arbitrary file writes through chat template names | High | Also affects transformers |
| GHSA-fgcw-684q-jj6r huggingface/transformers: Arbitrary Code Execution During Model Initialization in the LightGlue Model Loading Path | Critical | Also affects transformers |
| GHSA-29pf-2h5f-8g72 HuggingFace transformers vulnerable to remote code execution | High | Also affects transformers |
| GHSA-69w3-r845-3855 HuggingFace Transformers allows for arbitrary code execution in the `Trainer` class | High | Also affects transformers |
| PYSEC-2025-218 Hugging Face Transformers GLM4 Deserialization of Untrusted Data Remote Code Execution Vulnerability. | High | Also affects transformers |
| PYSEC-2025-217 Hugging Face Transformers X-CLIP Checkpoint Conversion Deserialization of Untrusted Data Remote Code Execution Vulnerability. | High | Also affects transformers |
| PYSEC-2025-216 Hugging Face Transformers HuBERT convert_config Code Injection Remote Code Execution Vulnerability. | High | Also affects transformers |
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