{"cve":"CVE-2025-61771","nvd":{"published":"2025-10-07T15:16:03.123","modified":"2026-10-19T16:10:00.260","status":"Analyzed","description":"Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser` stores non-file form fields (parts without a `filename`) entirely in memory as Ruby `String` objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx `client_max_body_size`) and validating and rejecting unusually large form fields at the application level.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-400"],"references":["https://github.com/rack/rack/commit/589127f4ac8b5cf11cf88fb0cd116ffed4d2181e","https://github.com/rack/rack/commit/d869fed663b113b95a74ad53e1b5cae6ab31f29e","https://github.com/rack/rack/commit/e08f78c656c9394d6737c022bde087e0f33336fd","https://github.com/rack/rack/security/advisories/GHSA-w9pc-fmgc-vxvw"],"products":["rack:rack"],"source":"nvd","synced_at":"2026-10-19T22:11:26.888974865+00:00"},"epss":{"cve":"CVE-2025-61771","score":0.00561,"percentile":0.4639,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-w9pc-fmgc-vxvw","url":"https://osv.dev/vulnerability/GHSA-w9pc-fmgc-vxvw","summary":"Rack: Multipart parser buffers large non‑file fields entirely in memory, enabling DoS (memory exhaustion)","modified":"2026-09-10T03:50:30.326446730Z","packages":[{"ecosystem":"RubyGems","name":"rack","purl":"pkg:gem/rack","ranges":["<2.2.19"],"fixed":["2.2.19"]},{"ecosystem":"RubyGems","name":"rack","purl":"pkg:gem/rack","ranges":[">=3.1 <3.1.17"],"fixed":["3.1.17"]},{"ecosystem":"RubyGems","name":"rack","purl":"pkg:gem/rack","ranges":[">=3.2 <3.2.2"],"fixed":["3.2.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}