CVEvulnerability

CVE-2026-39324

9.3 CRITICAL Published 2026-04-07 Modified 2026-10-26 Official page ↗
Status
Analyzed
Published
2026-04-07
Last modified
2026-10-26
Assigner
[email protected]
CVSS 4.0 ([email protected])
9.3 CRITICAL — 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1 ([email protected])
9.8 CRITICAL — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses
CWE-287, CWE-345, CWE-502, CWE-565

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.

Affected configurations

• rack rack-session (>= 2.0.0 < 2.1.2)

Related

Weakness · CWE (4)

  • CWE-287 Improper Authentication weakness
  • CWE-345 Insufficient Verification of Data Authenticity weakness
  • CWE-502 Deserialization of Untrusted Data weakness
  • CWE-565 Reliance on Cookies without Validation and Integrity Checking weakness

References