CVE-2026-5229

What is known

The Form Notify plugin for WordPress is vulnerable to Authentication Bypass in versions up to and including 1.1.10. This is due to the plugin trusting user-controlled cookie data to determine which WordPress account to authenticate after a LINE OAuth login. When LINE doesn't provide an email address (which is common), the plugin falls back to reading the 'form_notify_line_email' cookie value without verifying that the LINE account is associated with that email address. This makes it possible for unauthenticated attackers to gain access to any user account on the site, including administrator accounts, by completing a LINE OAuth flow with their own LINE account while injecting a malicious cookie containing the target victim's email address.

Business impact

Successful exploitation of CVE-2026-5229, a critical vulnerability (CVSS 9.8) affecting the affected product, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether the affected product is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

• NVD
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