{"id":"UBUNTU-CVE-2026-34829","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.","modified":"2026-04-13T14:33:42.966673Z","published":"2026-04-02T17:16:00Z","upstream":["CVE-2026-34829"],"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"}],"affected":[{"package":{"name":"ruby-rack","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack@1.5.2-3+deb8u3ubuntu1~esm10?arch=source&distro=esm-infra-legacy/trusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"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"],"ecosystem_specific":{"binaries":[{"binary_name":"librack-ruby","binary_version":"1.5.2-3+deb8u3ubuntu1~esm10"},{"binary_name":"librack-ruby1.8","binary_version":"1.5.2-3+deb8u3ubuntu1~esm10"},{"binary_name":"librack-ruby1.9.1","binary_version":"1.5.2-3+deb8u3ubuntu1~esm10"},{"binary_name":"ruby-rack","binary_version":"1.5.2-3+deb8u3ubuntu1~esm10"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34829.json"}},{"package":{"name":"ruby-rack","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack@1.6.4-3ubuntu0.2+esm9?arch=source&distro=esm-apps/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"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"],"ecosystem_specific":{"binaries":[{"binary_name":"ruby-rack","binary_version":"1.6.4-3ubuntu0.2+esm9"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34829.json"}},{"package":{"name":"ruby-rack","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack@1.6.4-4ubuntu0.2+esm9?arch=source&distro=esm-apps/bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"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"],"ecosystem_specific":{"binaries":[{"binary_name":"ruby-rack","binary_version":"1.6.4-4ubuntu0.2+esm9"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34829.json"}},{"package":{"name":"ruby-rack","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack@2.0.7-2ubuntu0.1+esm9?arch=source&distro=esm-apps/focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.6-3","2.0.7-2","2.0.7-2ubuntu0.1","2.0.7-2ubuntu0.1+esm1","2.0.7-2ubuntu0.1+esm2","2.0.7-2ubuntu0.1+esm3","2.0.7-2ubuntu0.1+esm4","2.0.7-2ubuntu0.1+esm5","2.0.7-2ubuntu0.1+esm6","2.0.7-2ubuntu0.1+esm7","2.0.7-2ubuntu0.1+esm8","2.0.7-2ubuntu0.1+esm9"],"ecosystem_specific":{"binaries":[{"binary_name":"ruby-rack","binary_version":"2.0.7-2ubuntu0.1+esm9"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34829.json"}},{"package":{"name":"ruby-rack","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack@2.1.4-5ubuntu1.2+esm2?arch=source&distro=esm-apps/jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"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":{"binaries":[{"binary_name":"ruby-rack","binary_version":"2.1.4-5ubuntu1.2+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34829.json"}},{"package":{"name":"ruby-rack","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack@2.2.7-1ubuntu0.6?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"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":{"binaries":[{"binary_name":"ruby-rack","binary_version":"2.2.7-1ubuntu0.6"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34829.json"}},{"package":{"name":"ruby-rack","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/ruby-rack@3.1.16-0.1ubuntu0.2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