setup/controllers/language.php in MODX Revolution 2.5.4-pl and earlier does not properly constrain the language parameter, which allows remote attackers to conduct Cookie-Bombing attacks and cause a denial of service (cookie quota exhaustion), or conduct HTTP Response Splitting attacks with resultant XSS, via an invalid parameter value.
Severity
CVSS 3.1
6.1 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS
0.9% chance of exploitation in the next 30 days; higher than 58% of CVEs (scores of 2026-10-31)