U.S. CISA adds a flaw in WebPros cPanel to its Known Exploited Vulnerabilities catalog
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2026-41940 | Missing-Authentication Bypass in WebPros cPanel & WHM (AuthBypass to RCE) 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. | 9.3 | 99% | KEV ransomware PoC ×4 |
| mass≈100,000+ internet-exposed cPanel/WHM servers, spanning tens of millions of hosted domains and millions of end users |
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The U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds a flaw in WebPros cPanel to its Known Exploited Vulnerabilities catalog
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added a flaw in Microsoft Defender, tracked as CVE-2026-41940 (CVSS score of 9.3), to its Known Exploited Vulnerabilities (KEV) catalog.
cPanel is a widely used web hosting control panel that lets users manage websites and servers through a graphical interface instead of command-line tools.
Cybersecurity experts at watchTowr first disclosed the flaw earlier this week and released a tool to help defenders identify vulnerable hosts in their estates.
“As we stated above, in-the-wild exploitation has already begun, according to KnownHost.” reads the advisory by watchTowr. “Therefore, we’re releasing our Detection Artifact Generator to enable defenders to identify vulnerable hosts in their estates.”
CVE-2026-41940 is an authentication bypass flaw affecting cPanel and WHM versions after 11.40. A weakness in the login flow allows remote attackers to skip or manipulate authentication checks, granting access to the control panel without valid credentials. This could let attackers manage hosting settings, access sensitive data, or take control of the server.
According to the Shadowserver Foundation, thousands of instances may be exposed.
— The Shadowserver Foundation (@Shadowserver) May 1, 2026
cPanel and watchTowr released tools to detect compromise and vulnerable hosts. Exploits date back to February. Namecheap warned customers of temporary access limits to mitigate risk.
According to Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities, FCEB agencies have to address the identified vulnerabilities by the due date to protect their networks against attacks exploiting the flaws in the catalog.
Experts also recommend that private organizations review the Catalog and address the vulnerabilities in their infrastructure.
CISA orders federal agencies to fix the vulnerability by May 3, 2026.
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