PYSEC-2026-1979

Vulnerability from pysec - Published: 2026-07-07 16:02 - Updated: 2026-07-07 17:25
VLAI
Details

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.

Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Impacted products
Name purl
transformers pkg:pypi/transformers
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "transformers",
        "purl": "pkg:pypi/transformers"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.49.0"
            },
            {
              "fixed": "4.51.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.49.0",
        "4.50.0",
        "4.50.1",
        "4.50.2",
        "4.50.3"
      ]
    }
  ],
  "aliases": [
    "CVE-2025-3262",
    "GHSA-489j-g2vx-39wf"
  ],
  "details": "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 \u0027almost matching\u0027 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.",
  "id": "PYSEC-2026-1979",
  "modified": "2026-07-07T17:25:42.734398Z",
  "published": "2026-07-07T16:02:56.726858Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-3262"
    },
    {
      "type": "WEB",
      "url": "https://github.com/huggingface/transformers/commit/0720e206c6ba28887e4d60ef60a6a089f6c1cc76"
    },
    {
      "type": "WEB",
      "url": "https://github.com/huggingface/transformers/commit/126abe3461762e5fc180e7e614391d1b4ab051ca"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/huggingface/transformers"
    },
    {
      "type": "WEB",
      "url": "https://huntr.com/bounties/ecf5ccc4-39e7-4fb3-b547-14a41d31a184"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/transformers"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-489j-g2vx-39wf"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Transformers vulnerable to ReDoS attack through its SETTING_RE variable"
}



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