Description
cPanel and WHM versions after 11.40 contain an authentication bypass vulnerability in the login flow that allows unauthenticated remote attackers to gain unauthorized access to the control panel.
CVSS breakdown
CVSS 4.0
Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality (Vulnerable System)
High
Integrity (Vulnerable System)
High
Availability (Vulnerable System)
High
Confidentiality (Subsequent System)
None
Integrity (Subsequent System)
None
Availability (Subsequent System)
None
CVSS 3.1
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected products
- WebPros / cPanel11.112.0.0 – 11.118.0.63
- WebPros / cPanel11.40.0.0 – 11.86.0.41
- WebPros / cPanel11.88.0.0 – 11.94.0.28
- WebPros / cPanel11.96.0.0 – 11.102.0.39
- WebPros / cPanel11.104.0.0 – 11.110.0.97
- WebPros / cPanel11.120.0.0 – 11.124.0.35
- WebPros / cPanel11.126.0.0 – 11.126.0.54
- WebPros / cPanel11.128.0.0 – 11.130.0.19
- WebPros / cPanel11.132.0.0 – 11.132.0.29
- WebPros / cPanel11.134.0.0 – 11.134.0.20
- WebPros / cPanel11.136.0.0 – 11.136.0.5
- WebPros / WHM11.136.0.0 – 11.136.0.5
- WebPros / WHM11.40.0.0 – 11.86.0.41
- WebPros / WHM11.88.0.0 – 11.94.0.28
- WebPros / WHM11.96.0.0 – 11.102.0.39
- WebPros / WHM11.104.0.0 – 11.110.0.97
- WebPros / WHM11.112.0.0 – 11.118.0.63
- WebPros / WHM11.120.0.0 – 11.124.0.35
- WebPros / WHM11.126.0.0 – 11.126.0.54
- WebPros / WHM11.128.0.0 – 11.130.0.19
- WebPros / WHM11.132.0.0 – 11.132.0.29
- WebPros / WHM11.134.0.0 – 11.134.0.20
- WebPros / WP Squared11.136.1.7 – 11.136.1.7
Exploits & PoCs
- nucleicPanel & WHM - Authentication Bypass via Session-File CRLF Injectionby watchtowr,hadrian.io,DhiyaneshDk
References
- MISChttps://support.cpanel.net/hc/en-us/articles/40073787579671-cPanel-WHM-Security-Update-04-28-2026
- MISChttps://docs.cpanel.net/release-notes/release-notes
- MISChttps://docs.wpsquared.com/changelogs/versions/changelog/#13617
- MISChttps://www.namecheap.com/status-updates/ongoing-critical-security-vulnerability-in-cpanel-april-28-2026
- VENDOR_ADVISORYhttps://www.vulncheck.com/advisories/cpanel-and-whm-authentication-bypass-via-login-flow