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.

References

• https://docs.cpanel.net/release-notes/release-notes
• https://docs.wpsquared.com/changelogs/versions/changelog/#13617
• https://support.cpanel.net/hc/en-us/articles/40073787579671-cPanel-WHM-Security-Update-04-28-2026
• https://www.namecheap.com/status-updates/ongoing-critical-security-vulnerability-in-cpanel-april-28-2026
• https://www.vulncheck.com/advisories/cpanel-and-whm-authentication-bypass-via-login-flow
• https://github.com/watchtowrlabs/watchTowr-vs-cPanel-WHM-AuthBypass-to-RCE.py
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-41940