{"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":"2026-07-22T20:45:22.038022538Z","published":"2026-04-02T17:16:00Z","related":["USN-8182-1"],"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"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8182-1"}],"affected":[{"package":{"name":"ruby-rack","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack?arch=source&distro=esm-infra-legacy%2Ftrusty"},"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","1.5.2-3+deb8u3ubuntu1~esm11"],"ecosystem_specific":{"binaries":[{"binary_version":"1.5.2-3+deb8u3ubuntu1~esm11","binary_name":"librack-ruby"},{"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"}]},"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?arch=source&distro=esm-apps%2Fxenial"},"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","1.6.4-3ubuntu0.2+esm10"],"ecosystem_specific":{"binaries":[{"binary_version":"1.6.4-3ubuntu0.2+esm10","binary_name":"ruby-rack"}]},"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?arch=source&distro=esm-apps%2Fbionic"},"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","1.6.4-4ubuntu0.2+esm10"],"ecosystem_specific":{"binaries":[{"binary_name":"ruby-rack","binary_version":"1.6.4-4ubuntu0.2+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:22.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack?arch=source&distro=esm-apps%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.4-5ubuntu1.2+esm3"}]}],"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+esm3"}],"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro"},"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?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.7-1ubuntu0.7"}]}],"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":"2.2.7-1ubuntu0.7"}],"availability":"No subscription required"},"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?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.16-0.1ubuntu0.3"}]}],"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_version":"3.1.16-0.1ubuntu0.3","binary_name":"ruby-rack"}],"availability":"No subscription required"},"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:26.04:LTS","purl":"pkg:deb/ubuntu/ruby-rack?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.16-0.1","3.1.18-1","3.1.18-1build1","3.2.4-1ubuntu1"],"ecosystem_specific":{"binaries":[{"binary_name":"ruby-rack","binary_version":"3.2.4-1ubuntu1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34829.json"}}],"schema_version":"1.7.5","severity":[{"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":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}