PatchTheCVECVE-2026-117549: @fastify/secure-session is a session plugin for Fastify that stores an encrypted session in a cookie
CVE-2026-117549 is a medium-severity flaw (CVSS 4.2) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
@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
Why this priority
- No elevated risk signals yet
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 4.2 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | High |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | n/a |
| CISA exploited list | No |
| Weakness | CWE-347 |
| Published | 2026-11-02 |
| Last modified | 2026-11-02 |
Last updated 2026-11-02 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Timeline
- Published CVE record published
- Updated Record last modified
Advisories and coverage
Research and news
- VulDB Recent Entries: CVE-2026-117549 | fastify fastify-secure-session up to 8.4.1 Cookie Unsign Routine improper authentication 2026-11-02
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-117549?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-117549 being exploited?
CVE-2026-117549 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-117549 affect?
CVE-2026-117549 affects affected software. Severity is medium (CVSS 4.2). @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
How urgent is CVE-2026-117549?
Priority 15/100. No elevated risk signals yet.