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DEBIAN-CVE-2026-34827

Type: advisorySource: OSV1 source record

Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6.

Announced Source revision 1
Original source ↗

DEBIAN-CVE-2026-34827

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:DEBIAN-CVE-2026-34827

ruby-rack

Source reference: /affected/0/package/name

Affected versions
3.1.16-0.1

Source reference: /affected/0/versions

3.1.18-1

Source reference: /affected/0/versions

3.1.18-1~deb13u1

Source reference: /affected/0/versions

3.1.20-0+deb13u1

Source reference: /affected/0/versions

Fixed versions
3.1.20-0+deb13u2

Source reference: /affected/0/ranges

Prerequisites
Not stated in this record

ruby-rack

Source reference: /affected/1/package/name

Affected versions
3.1.16-0.1

Source reference: /affected/1/versions

3.1.18-1

Source reference: /affected/1/versions

3.1.18-1~deb13u1

Source reference: /affected/1/versions

3.2.4-1

Source reference: /affected/1/versions

3.2.5-1

Source reference: /affected/1/versions

3.2.5-2

Source reference: /affected/1/versions

3.2.6-1

Source reference: /affected/1/versions

Fixed versions
3.2.6-2

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "3.1.20-0+deb13u2"
          }
        ]
      }
    ],
    "package": {
      "name": "ruby-rack",
      "purl": "pkg:deb/debian/ruby-rack?arch=source&distro=trixie",
      "ecosystem": "Debian:13"
    },
    "versions": [
      "3.1.16-0.1",
      "3.1.18-1",
      "3.1.18-1~deb13u1",
      "3.1.20-0+deb13u1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-34827.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "ranges": [
      {
        "type": "ECOSYSTEM",
        "events": [
          {
            "introduced": "0"
          },
          {
            "fixed": "3.2.6-2"
          }
        ]
      }
    ],
    "package": {
      "name": "ruby-rack",
      "purl": "pkg:deb/debian/ruby-rack?arch=source&distro=forky",
      "ecosystem": "Debian:14"
    },
    "versions": [
      "3.1.16-0.1",
      "3.1.18-1",
      "3.1.18-1~deb13u1",
      "3.2.4-1",
      "3.2.5-1",
      "3.2.5-2",
      "3.2.6-1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-34827.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#57539 · Revision 1
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Publisher date
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