Auth bypass in Rack Rack-session
CVE-2026-39324
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 ba…
Vulnerability class: Broken Authentication
EPSS: 0.003 (18.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Rack Rack-session — versions >= 2.0.0, < 2.1.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-39324?
- CVE-2026-39324 is a critical-severity vulnerability in Rack Rack-session, classified under Improper Authentication. CVSS score: 9.8/10. Published 2026-04-07.
- How severe is CVE-2026-39324?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2026-39324 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.