{"cve":"CVE-2026-117549","nvd":{"published":"2026-11-02T11:17:30.997","modified":"2026-11-02T11:17:30.997","status":"Received","description":"@fastify/secure-session is a session plugin for Fastify that stores an encrypted session in a cookie. In versions 7.5.0 through 8.4.1, when the plugin is configured with the signed cookie option, it calls the cookie unsign routine but, when the signature check reports the value as invalid, still passes the original cookie value to the session decoder, so a session whose signature did not validate is decrypted anyway. The practical effect appears when an application supplies the cookie signing secret independently of the session encryption key and rotates only the signing secret to retire existing sessions while keeping the encryption key active, because a holder of an old session cookie can strip the now obsolete signature and keep using the session. The attacker must already possess an unexpired encrypted session cookie and needs neither secret, and cannot forge session data, extend expiry, or survive rotation of the encryption key. The issue is fixed in @fastify/secure-session 8.4.2, which no longer decodes the session when the signed cookie option is set and the signature check fails, and users should upgrade to 8.4.2 or later. As a workaround, rotate the session encryption key rather than relying on rotation of the cookie signing secret alone.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N","score":4.2},"cwes":["CWE-347"],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/fastify/fastify-secure-session/security/advisories/GHSA-4cgq-x5f7-r8jv"],"reference_tags":[{"url":"https://cna.openjsf.org/security-advisories.html","tags":[]},{"url":"https://github.com/fastify/fastify-secure-session/security/advisories/GHSA-4cgq-x5f7-r8jv","tags":[]}],"products":[],"affected":[],"source":"nvd","synced_at":"2026-11-02T11:46:51.329548709+00:00"},"epss":null,"kev":null,"exploits":[],"weaknesses":[{"name":"Improper Verification of Cryptographic Signature","common_name":null,"deprecated":false,"replaced_by":[],"id":"CWE-347"}],"osv":[],"fixed":[],"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.","Public exploits: links to the Exploit Database (https://www.exploit-db.com, by OffSec; index under GPL-2.0), Rapid7's Metasploit Framework modules (https://github.com/rapid7/metasploit-framework, BSD-3-Clause) and ProjectDiscovery's nuclei templates (https://github.com/projectdiscovery/nuclei-templates, MIT). Only the links, titles and dates are stored; no exploit code is fetched or served.","CWE names and descriptions: MITRE's Common Weakness Enumeration (https://cwe.mitre.org), Copyright © 2006–2026, The MITRE Corporation, under the CWE terms of use (https://cwe.mitre.org/about/termsofuse.html). CWE is a trademark of The MITRE Corporation."]}