{"id":"CVE-2026-34829","summary":"Rack: Denial of Service via Unbounded Multipart File Upload Without Content-Length","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.","aliases":["GHSA-8vqr-qjwx-82mw"],"modified":"2026-04-09T11:17:03.803960Z","published":"2026-04-02T16:46:47.357Z","related":["CGA-c3rr-m9xh-gmfw"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34829.json","cwe_ids":["CWE-400","CWE-770"],"cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34829.json"},{"type":"ADVISORY","url":"https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34829"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/rack/rack","events":[{"introduced":"0"},{"fixed":"f2af0c8f869193fa7bb7d20b619b3003418e1055"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"2.2.23"}]}},{"type":"GIT","repo":"https://github.com/rack/rack","events":[{"introduced":"572a42a705b423ce98ef4e81435d4f60fb0ae53d"},{"fixed":"ae8431120e66e92d1885ab8ec0a553d9cad5ec13"}],"database_specific":{"versions":[{"introduced":"3.0.0.beta1"},{"fixed":"3.1.21"}]}},{"type":"GIT","repo":"https://github.com/rack/rack","events":[{"introduced":"b68251c03788ff39d4a4b25424df7360426e4afd"},{"fixed":"e1f22fdbe99afd2126b6fbf05bb12399359574b7"}],"database_specific":{"versions":[{"introduced":"3.2.0"},{"fixed":"3.2.6"}]}}],"versions":["0.1","0.2","0.3","1.0","1.3.0","1.3.0.beta","1.3.0.beta2","1.4.0","1.4.1","1.5.0","1.5.1","1.6.0.beta","2.0.0","2.0.0.alpha","2.0.0.rc1","2.0.1","2.1.0","2.2.0","2.2.3","2.2.4","3.0.0","3.0.0.beta1","3.0.0.rc1","v2.2.1","v2.2.10","v2.2.11","v2.2.12","v2.2.13","v2.2.14","v2.2.15","v2.2.16","v2.2.17","v2.2.18","v2.2.19","v2.2.2","v2.2.20","v2.2.21","v2.2.22","v2.2.5","v2.2.6","v2.2.6.1","v2.2.6.2","v2.2.7","v2.2.8","v2.2.9","v3.1.0","v3.1.10","v3.1.11","v3.1.12","v3.1.13","v3.1.14","v3.1.15","v3.1.16","v3.1.17","v3.1.18","v3.1.19","v3.1.2","v3.1.20","v3.1.3","v3.1.4","v3.1.5","v3.1.6","v3.1.7","v3.1.8","v3.1.9","v3.2.0","v3.2.1","v3.2.2","v3.2.3","v3.2.4","v3.2.5"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/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"}]}