UBUNTU-CVE-2026-34829 (CVE-2026-34829)

Vulnerability from osv_ubuntu – Published: 2026-04-02 17:16 – Updated: 2026-07-22 18:37 – Source website
VLAI
Details

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "librack-ruby",
            "binary_version": "1.5.2-3+deb8u3ubuntu1~esm11"
          },
          {
            "binary_name": "librack-ruby1.8",
            "binary_version": "1.5.2-3+deb8u3ubuntu1~esm11"
          },
          {
            "binary_name": "librack-ruby1.9.1",
            "binary_version": "1.5.2-3+deb8u3ubuntu1~esm11"
          },
          {
            "binary_name": "ruby-rack",
            "binary_version": "1.5.2-3+deb8u3ubuntu1~esm11"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "ruby-rack",
        "purl": "pkg:deb/ubuntu/ruby-rack@1.5.2-3+deb8u3ubuntu1~esm11?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.5.2-1",
        "1.5.2-1ubuntu0.1~esm1",
        "1.5.2-3+deb8u3ubuntu1~esm2",
        "1.5.2-3+deb8u3ubuntu1~esm3",
        "1.5.2-3+deb8u3ubuntu1~esm4",
        "1.5.2-3+deb8u3ubuntu1~esm6",
        "1.5.2-3+deb8u3ubuntu1~esm7",
        "1.5.2-3+deb8u3ubuntu1~esm8",
        "1.5.2-3+deb8u3ubuntu1~esm9",
        "1.5.2-3+deb8u3ubuntu1~esm10",
        "1.5.2-3+deb8u3ubuntu1~esm11"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "ruby-rack",
            "binary_version": "1.6.4-3ubuntu0.2+esm10"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "ruby-rack",
        "purl": "pkg:deb/ubuntu/ruby-rack@1.6.4-3ubuntu0.2+esm10?arch=source\u0026distro=esm-apps/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.5.2-4",
        "1.6.4-2",
        "1.6.4-3",
        "1.6.4-3ubuntu0.1",
        "1.6.4-3ubuntu0.2",
        "1.6.4-3ubuntu0.2+esm1",
        "1.6.4-3ubuntu0.2+esm2",
        "1.6.4-3ubuntu0.2+esm4",
        "1.6.4-3ubuntu0.2+esm5",
        "1.6.4-3ubuntu0.2+esm6",
        "1.6.4-3ubuntu0.2+esm7",
        "1.6.4-3ubuntu0.2+esm8",
        "1.6.4-3ubuntu0.2+esm9",
        "1.6.4-3ubuntu0.2+esm10"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "ruby-rack",
            "binary_version": "1.6.4-4ubuntu0.2+esm10"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "ruby-rack",
        "purl": "pkg:deb/ubuntu/ruby-rack@1.6.4-4ubuntu0.2+esm10?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6.4-4",
        "1.6.4-4ubuntu0.1",
        "1.6.4-4ubuntu0.2",
        "1.6.4-4ubuntu0.2+esm1",
        "1.6.4-4ubuntu0.2+esm2",
        "1.6.4-4ubuntu0.2+esm4",
        "1.6.4-4ubuntu0.2+esm5",
        "1.6.4-4ubuntu0.2+esm6",
        "1.6.4-4ubuntu0.2+esm7",
        "1.6.4-4ubuntu0.2+esm8",
        "1.6.4-4ubuntu0.2+esm9",
        "1.6.4-4ubuntu0.2+esm10"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "ruby-rack",
            "binary_version": "2.1.4-5ubuntu1.2+esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "ruby-rack",
        "purl": "pkg:deb/ubuntu/ruby-rack@2.1.4-5ubuntu1.2+esm3?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.4-5ubuntu1.2+esm3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.1.4-3",
        "2.1.4-4",
        "2.1.4-5",
        "2.1.4-5ubuntu1",
        "2.1.4-5ubuntu1+esm2",
        "2.1.4-5ubuntu1+esm3",
        "2.1.4-5ubuntu1+esm4",
        "2.1.4-5ubuntu1+esm5",
        "2.1.4-5ubuntu1.1",
        "2.1.4-5ubuntu1.1+esm1",
        "2.1.4-5ubuntu1.1+esm2",
        "2.1.4-5ubuntu1.2",
        "2.1.4-5ubuntu1.2+esm1",
        "2.1.4-5ubuntu1.2+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "ruby-rack",
            "binary_version": "2.2.7-1ubuntu0.7"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "ruby-rack",
        "purl": "pkg:deb/ubuntu/ruby-rack@2.2.7-1ubuntu0.7?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.2.7-1ubuntu0.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.2.4-3",
        "2.2.7-1",
        "2.2.7-1ubuntu0.1",
        "2.2.7-1ubuntu0.2",
        "2.2.7-1ubuntu0.3",
        "2.2.7-1ubuntu0.4",
        "2.2.7-1ubuntu0.5",
        "2.2.7-1ubuntu0.6"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "ruby-rack",
            "binary_version": "3.1.16-0.1ubuntu0.3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "ruby-rack",
        "purl": "pkg:deb/ubuntu/ruby-rack@3.1.16-0.1ubuntu0.3?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.16-0.1ubuntu0.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.2.7-1.1",
        "3.1.16-0.1",
        "3.1.16-0.1ubuntu0.1",
        "3.1.16-0.1ubuntu0.2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "ruby-rack",
            "binary_version": "3.2.4-1ubuntu1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "ruby-rack",
        "purl": "pkg:deb/ubuntu/ruby-rack@3.2.4-1ubuntu1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.1.16-0.1",
        "3.1.18-1",
        "3.1.18-1build1",
        "3.2.4-1ubuntu1"
      ]
    }
  ],
  "aliases": [],
  "details": "Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.",
  "id": "UBUNTU-CVE-2026-34829",
  "modified": "2026-07-22T18:37:15Z",
  "published": "2026-04-02T17:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-34829"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-34829"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8182-1"
    }
  ],
  "related": [
    "USN-8182-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-34829"
  ]
}



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