Critical cPanel Flaw Could Let One Hosting Customer Take Root Control of a Whole Server

CVE-2026-41940 is a critical missing-authentication flaw (CWE-306) in the login flow of WebPros cPanel & WHM (versions after 11.40) and WP2 (WordPress Squared) that lets unauthenticated remote attackers bypass authentication and gain unauthorized access to the control panel. Because no privileges, user interaction, or special conditions are required, any attacker who can reach the login endpoint over the network can attempt it. Beyond control-panel account takeover, public proofs of concept — including watchTowr's 'AuthBypass to RCE' exploit — show the flaw can be chained to remote code execution, and reporting indicates a single hosting customer could obtain root control of an entire shared server. Any hosting provider, MSP, reseller, or organization running cPanel/WHM or WP Squared is affected; cPanel is the dominant commercial hosting control panel, implying a very large installed base of shared-hosting servers and hosted domains. Exploitation is confirmed in the wild: CISA added it to the KEV on 2026-04-30 with known ransomware use, EPSS assigns a 98.5% probability of exploitation within 30 days (100th percentile), and multiple threat actors are actively exploiting it, including against government and MSP networks.

Do: Patch immediately per WebPros' advisory — the source data does not specify fixed version numbers, so follow vendor instructions for exact patched releases; CISA KEV/BOD 22-01 requires federal agencies to apply mitigations or discontinue use by the stated deadline (reported as Sunday). Until patched, restrict access to the cPanel/WHM login interface (IP allowlisting, VPN, or limiting management-interface exposure) and hunt for indicators of compromise such as unexpected control-panel logins, new admin accounts, webshells, or ransomware artifacts. The referenced public PoCs can be used to validate whether your instances are exploitable.

CVE-2026-48172 is a critical privilege-escalation flaw (CWE-266, incorrect privilege assignment) in the LiteSpeed User-End cPanel plugin before 2.4.5, stemming from mishandling of the plugin's Redis enable/disable feature. It is exploitable over the network without authentication or user interaction (CVSS 4.0: AV:N/AC:L/PR:N/UI:N), and exploitation leaves traces of requests to the cPanel API's redisAble function in cPanel logs. An attacker who exploits it can elevate privileges to possibly root on the hosting server, meaning a single attacker could take control of every account and site hosted on that server. At risk are hosting providers and organizations running cPanel/WHM with the LiteSpeed cPanel plugin (and the related WHM plugin), a common premium web-server setup on multi-tenant shared-hosting platforms. The flaw was exploited in the wild in May 2026, was added to CISA's KEV catalog on 2026-05-26, and carries an EPSS of 18.9% (97th percentile); no public PoC is known.

Do: Upgrade the LiteSpeed User-End cPanel plugin to at least version 2.4.7 (versions before 2.4.5 are affected; 2.4.7 is the recommended minimum). Hunt for exploitation by running grep -rE "cpanel_jsonapi_func=redisAble" /var/cpanel/logs /usr/local/cpanel/logs/ 2>/dev/null in Bash: no output means you were not hit, while hits should be validated (confirm the listed IPs are legitimate, block any that are not, and review system logs for actions taken by those IPs). Because this is a CISA KEV entry (added 2026-05-26), apply the vendor fix per BOD 22-01 timelines or discontinue use of the product if mitigations are unavailable.

The LiteSpeed cPanel plugin, as distributed through the LiteSpeed WHM plugin, before version 2.4.8 (WHM plugin 5.3.2.0) mishandles UNIX symbolic links supplied by users (CWE-61). An attacker who already has FTP or web shell access to any account on a shared hosting server running CloudLinux/CageFS can plant a crafted symlink that the privileged plugin follows, letting them act beyond their own account scope — reportedly gaining root control of the entire server (CVSS scope change, C:H/I:H/A:H). Any hosting provider running vulnerable versions of the LiteSpeed cPanel/WHM plugin is affected, and because this is shared hosting, a single malicious tenant endangers other customers on the same server. The flaw was exploited in the wild in May 2026, was added to CISA's Known Exploited Vulnerabilities catalog on 2026-06-15 (BOD 26-04 remediation obligations apply), and has a 1.4% 30-day EPSS; no public proof-of-concept is known.

Do: Upgrade the LiteSpeed cPanel plugin to 2.4.8 or later via the LiteSpeed WHM plugin 5.3.2.0 or later, following vendor instructions to meet CISA KEV/BOD 26-04 timelines. Until patched, restrict or monitor FTP and web shell access on affected shared hosting servers and review logs for signs of privilege escalation during and since May 2026; if mitigations are unavailable, follow applicable BOD 26-04 guidance for cloud services or discontinue use.

HTTP Smuggling in cPanel allows potential leak of credentials.

Improper preservation of SQL mode when renaming databases in cPanel allows execution of SQL in root context.

cPanel 11.138.0.0 and earlier contains an eval injection flaw (CWE-95) in which attacker-controlled input reaches dynamic code evaluation without proper neutralization. A remote attacker holding any authenticated account on a cPanel server, such as an ordinary hosting customer, can trigger the flaw with crafted input and no user interaction. Successful exploitation yields arbitrary code execution as root, meaning a single low-privilege tenant can compromise the entire server and every site hosted on it. All deployments running version 11.138.0.0 or earlier are affected, which at disclosure covers essentially all active cPanel servers given that this was the current release. No public proof-of-concept or confirmed in-the-wild exploitation is known; the issue is not in CISA KEV and EPSS assigns only a 0.9% probability of exploitation within 30 days.

Do: Upgrade cPanel/WHM to a fixed release above 11.138.0.0 published under WebPros advisory AV26-861, prioritizing multi-tenant shared servers where any customer account can reach the vulnerable code. Until patched, restrict shell and feature access for untrusted accounts and review authentication logs and unexpected root-owned processes. No workaround is documented in the available data, so updating is the primary action.