CVE-2025-3262 Regular Expression Denial of Service (ReDoS) in huggingface/transformers
Attackers can cause denial of service in huggingface/transformers by submitting crafted inputs that trigger inefficient regex backtracking.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-3262?
CVE-2025-3262 is a medium-severity denial of service vulnerability in huggingface/transformers, published on 7 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-1333
Which versions are affected by CVE-2025-3262?
3 open source packages ship an affected version, including transformers. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
transformers PyPI | From 4.49.0 | 4.51.0 |
transformers PyPI | From 4.49.0 | 4.51.0 |
transformers PyPI | From 4.49.0 | 4.51.0 |
Products include Huggingface Transformers.
How do I fix CVE-2025-3262?
Upgrade transformers to 4.51.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-3262 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-3262 exists.
Other vulnerabilities in huggingface/transformers
- CVE-2023-7018 Deserialization of Untrusted Data in huggingface/transformers
- CVE-2023-6730 Deserialization of Untrusted Data in huggingface/transformers
- CVE-2024-11393 Hugging Face Transformers MaskFormer Model Deserialization of Untrusted Data Remote Code Execution Vulnerability
- CVE-2024-11394 Hugging Face Transformers Trax Model Deserialization of Untrusted Data Remote Code Execution Vulnerability
- CVE-2026-5241 Policy Bypass in LightGlue Nested Config Resolution in huggingface/transformers
Sources
Also known as GHSA-489j-g2vx-39wf, PYSEC-2026-1979.