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DEBIAN-CVE-2026-26961

Type: advisorySource: OSV1 source record

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser extracts the boundary parameter from multipart/form-data using a greedy regular expression. When a Content-Type header contains multiple boundary parameters, Rack selects the last one rather than the first. In deployments where an upstream proxy, WAF, or intermediary interprets the first boundary parameter, this mismatch can allow an attacker to smuggle multipart content past upstream inspection and have Rack parse a different body structure than the intermediary validated. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

Announced Source revision 1
Original source ↗

DEBIAN-CVE-2026-26961

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-2026-26961

ruby-rack

Source reference: /affected/0/package/name

Affected versions
2.2.13-1~deb12u1

Source reference: /affected/0/versions

2.2.20-0+deb12u1

Source reference: /affected/0/versions

2.2.22-0+deb12u1

Source reference: /affected/0/versions

2.2.6.4-1

Source reference: /affected/0/versions

2.2.6.4-1+deb12u1

Source reference: /affected/0/versions

2.2.7-1

Source reference: /affected/0/versions

2.2.7-1.1

Source reference: /affected/0/versions

Fixed versions
2.2.22-0+deb12u2

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

3.1.20-0+deb13u1

Source reference: /affected/1/versions

Fixed versions
3.1.20-0+deb13u2

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

ruby-rack

Source reference: /affected/2/package/name

Affected versions
3.1.16-0.1

Source reference: /affected/2/versions

3.1.18-1

Source reference: /affected/2/versions

3.1.18-1~deb13u1

Source reference: /affected/2/versions

3.2.4-1

Source reference: /affected/2/versions

3.2.5-1

Source reference: /affected/2/versions

3.2.5-2

Source reference: /affected/2/versions

3.2.6-1

Source reference: /affected/2/versions

Fixed versions
3.2.6-2

Source reference: /affected/2/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": "2.2.22-0+deb12u2"
          }
        ]
      }
    ],
    "package": {
      "name": "ruby-rack",
      "purl": "pkg:deb/debian/ruby-rack?arch=source&distro=bookworm",
      "ecosystem": "Debian:12"
    },
    "versions": [
      "2.2.13-1~deb12u1",
      "2.2.20-0+deb12u1",
      "2.2.22-0+deb12u1",
      "2.2.6.4-1",
      "2.2.6.4-1+deb12u1",
      "2.2.7-1",
      "2.2.7-1.1"
    ],
    "database_specific": {
      "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-26961.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  },
  {
    "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-2026-26961.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-2026-26961.json"
    },
    "ecosystem_specific": {
      "urgency": "not yet assigned"
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#55884 · Revision 1
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Publisher date
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