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 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 v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/rack/rack-session/security/advisories/GHSA-33qg-7wpp-89cq	Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:rack:rack-session:*:*:*:*:*:ruby:*:*

History

15 Apr 2026, 20:17

Type	Values Removed	Values Added
References	~~() https://github.com/rack/rack-session/security/advisories/GHSA-33qg-7wpp-89cq -~~	() https://github.com/rack/rack-session/security/advisories/GHSA-33qg-7wpp-89cq - Mitigation, Vendor Advisory
First Time		Rack Rack rack-session
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.8
CPE		cpe:2.3:a:rack:rack-session::::::ruby::*

07 Apr 2026, 18:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-04-07 18:16

Updated : 2026-04-15 20:17

NVD link : CVE-2026-39324

Mitre link : CVE-2026-39324

CVE.ORG link : CVE-2026-39324

JSON object : View

Products Affected

rack

rack-session

CWE

CWE-287

Improper Authentication

CWE-345

Insufficient Verification of Data Authenticity

CWE-502

Deserialization of Untrusted Data

CWE-565

Reliance on Cookies without Validation and Integrity Checking

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