{"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":"2026-05-28T03:54:15.131177053Z","published":"2026-04-02T16:46:47.357Z","related":["CGA-c3rr-m9xh-gmfw","SUSE-SU-2026:1745-1","SUSE-SU-2026:1964-1","openSUSE-SU-2026:10508-1"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-400","CWE-770"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34829.json"},"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":"b68251c03788ff39d4a4b25424df7360426e4afd"},{"fixed":"e1f22fdbe99afd2126b6fbf05bb12399359574b7"}]}],"versions":["v3.2.5","v3.2.4","v3.2.3","v3.2.2","v3.2.1","v3.2.0"],"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"}]}