{"cve":"CVE-2025-61921","nvd":{"published":"2025-10-10T20:15:38.067","modified":"2026-10-19T16:10:00.260","status":"Analyzed","description":"Sinatra is a domain-specific language for creating web applications in Ruby. In versions prior to 4.2.0, there is a denial of service vulnerability in the `If-Match` and `If-None-Match` header parsing component of Sinatra, if the `etag` method is used when constructing the response. Carefully crafted input can cause `If-Match` and `If-None-Match` header parsing in Sinatra to take an unexpected amount of time, possibly resulting in a denial of service attack vector. This header is typically involved in generating the `ETag` header value. Any applications that use the `etag` method when generating a response are impacted. Version 4.2.0 fixes the issue.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U","score":2.7},"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-1333"],"references":["https://bugs.ruby-lang.org/issues/19104","https://github.com/sinatra/sinatra/issues/2120","https://github.com/sinatra/sinatra/pull/1823","https://github.com/sinatra/sinatra/pull/2121","https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q"],"products":["sinatrarb:sinatra"],"source":"nvd","synced_at":"2026-10-19T22:11:26.888974865+00:00"},"epss":{"cve":"CVE-2025-61921","score":0.00495,"percentile":0.42187,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-mr3q-g2mv-mr4q","url":"https://osv.dev/vulnerability/GHSA-mr3q-g2mv-mr4q","summary":"Sinatra is vulnerable to ReDoS through ETag header value generation","modified":"2026-09-10T03:50:30.082629594Z","packages":[{"ecosystem":"RubyGems","name":"sinatra","purl":"pkg:gem/sinatra","ranges":["<4.2.0"],"fixed":["4.2.0"]}]}],"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."]}