CVE-2026-125111

Full vulnerability record from the local CVENow database.

Description

Rack is a modular Ruby web server interface. Prior to 2.2.25, 3.1.23, and 3.2.8, Rack::Multipart::Parser can retain parsed data in its internal StringScanner buffer when reads end inside or immediately after multipart headers. An unauthenticated attacker can align many small parts with rack.multipart.buffer_size boundaries so the buffer grows with the request despite per-field, header, and preamble limits, causing a worker to exhaust memory. The attack requires only a well-formed multipart body and affects applications that parse multipart requests. This issue is fixed in versions 2.2.25, 3.1.23, and 3.2.8.

Severity

HIGH

CVSS score

7.5 (v3.1)

Vulnerability status

Received

Source identifier

[email protected]

Published

2026-11-09 22:18:42.433000

Last modified

2026-11-09 22:18:42.433000

View original CVE JSON

{
  "id": "CVE-2026-125111",
  "sourceIdentifier": "[email protected]",
  "published": "2026-11-09T22:18:42.433",
  "lastModified": "2026-11-09T22:18:42.433",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Rack is a modular Ruby web server interface. Prior to 2.2.25, 3.1.23, and 3.2.8, Rack::Multipart::Parser can retain parsed data in its internal StringScanner buffer when reads end inside or immediately after multipart headers. An unauthenticated attacker can align many small parts with rack.multipart.buffer_size boundaries so the buffer grows with the request despite per-field, header, and preamble limits, causing a worker to exhaust memory. The attack requires only a well-formed multipart body and affects applications that parse multipart requests. This issue is fixed in versions 2.2.25, 3.1.23, and 3.2.8."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "rack",
          "product": "rack",
          "versions": [
            {
              "version": "< 2.2.25",
              "status": "affected"
            },
            {
              "version": ">= 3.0, < 3.1.23",
              "status": "affected"
            },
            {
              "version": ">= 3.2, < 3.2.8",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Primary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/rack/rack/commit/244e75a840cee0823f86d5d01dc374505a8abed8",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/rack/rack/commit/2eaa5b1026a03a43b6537b1a0b233707ba887702",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/rack/rack/commit/c9b4698595050838342bd3b5a0fc9ab908065f8f",
      "source": "[email protected]"
    },
    {
      "url": "https://github.com/rack/rack/security/advisories/GHSA-5v64-555j-wjxm",
      "source": "[email protected]"
    }
  ]
}