CodeIgniter before 2.2.0 makes it easier for attackers to decode session cookies by leveraging fallback to a custom XOR-based encryption scheme when the Mcrypt extension for PHP is not available.
Severity
CVSS 3.0
9.8 critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
37% chance of exploitation in the next 30 days; higher than 98% of CVEs (scores of 2026-10-31)