{"cve":"CVE-2026-39324","nvd":{"published":"2026-04-07T18:16:43.387","modified":"2026-10-26T21:10:00.170","status":"Analyzed","description":"Rack::Session is a session management implementation for Rack. From 2.0.0 to before 2.1.2, Rack::Session::Cookie incorrectly handles decryption failures when configured with secrets:. If cookie decryption fails, the implementation falls back to a default decoder instead of rejecting the cookie. This allows an unauthenticated attacker to supply a crafted session cookie that is accepted as valid session data without knowledge of any configured secret. Because this mechanism is used to load session state, an attacker can manipulate session contents and potentially gain unauthorized access. This vulnerability is fixed in 2.1.2.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","score":9.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-287","CWE-345","CWE-502","CWE-565"],"references":["https://github.com/rack/rack-session/security/advisories/GHSA-33qg-7wpp-89cq"],"products":["rack:rack-session"],"source":"nvd","synced_at":"2026-10-26T21:38:48.864438205+00:00"},"epss":{"cve":"CVE-2026-39324","score":0.0027,"percentile":0.18993,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-33qg-7wpp-89cq","url":"https://osv.dev/vulnerability/GHSA-33qg-7wpp-89cq","summary":"Rack::Session::Cookie secrets: decrypt failure fallback enables secretless session forgery and Marshal deserialization","modified":"2026-09-10T03:50:42.369413216Z","packages":[{"ecosystem":"RubyGems","name":"rack-session","purl":"pkg:gem/rack-session","ranges":[">=2.0.0 <2.1.2"],"fixed":["2.1.2"]}]}],"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."]}