WAF rule added for cPanel authentication bypass CVE-2026-41940
An emergency WAF rule has been deployed to block exploitation of CVE-2026-41940, a critical authentication bypass vulnerability in cPanel & WHM that allows unauthenticated attackers to gain unauthorized administrative access. Cloudflare strongly recommends applying vendor patches immediately to mitigate the underlying vulnerability.
This emergency release introduces a new rule to block a cPanel & WHM Authentication Bypass related to CVE-2026-41940.
Key Findings
- CVE-2026-41940: A critical authentication bypass vulnerability in cPanel & WHM allows unauthenticated remote attackers to bypass authentication mechanisms and gain unauthorized administrative access to the web hosting control panel. This vulnerability affects the session validation logic, enabling attackers to craft malicious requests that circumvent normal authentication checks.
Impact
Successful exploitation allows unauthenticated attackers to gain administrative control over affected cPanel & WHM installations. This leads to complete server compromise, potential theft or manipulation of hosted data, and significant service disruption across managed environments.
We strongly recommend applying official vendor patches for cPanel & WHM immediately to address the underlying vulnerability.
| Ruleset | Rule ID | Legacy Rule ID | Description | Previous Action | New Action | Comments |
|---|---|---|---|---|---|---|
| Cloudflare Managed Ruleset | ...eb2b9e2f | N/A | cPanel - Auth Bypass - CVE:CVE-2026-41940 | N/A | Block | This is a new detection. |
Source: original entry ↗
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