Inefficient regular expression complexity in transformers - CVE-2025-3264

Vulnerability details

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to regular expression pattern `s*trys*:.*?except.*?:` used to filter out try/except blocks from Python code, which can be exploited to cause excessive CPU consumption through crafted input strings due to catastrophic backtracking. A remote attacker can pass specially crafted data to the application and perform regular expression denial of service (ReDos) attack.

Affected software

How to mitigate CVE-2025-3264

External References

• https://github.com/huggingface/transformers/commit/0720e206c6ba28887e4d60ef60a6a089f6c1cc76
• https://huntr.com/bounties/3c6f7822-9992-476d-8cf0-b0b1623427df

Related Security Bulletins

• Inefficient regular expression complexity in Hugging Face Transformers library