CVE-2026-106648 in Royal Elementor Addons Plugin
Summary
by MITRE • 10/28/2026
The Royal Elementor Addons WordPress plugin before 1.7.1070 does not validate submitted form field values before substituting them into the recipient addresses of its form notification emails, allowing unauthenticated attackers to replace the recipient list and relay attacker-composed email from the site's own domain when a recipient field is configured to echo a submitted value.
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified in Royal Elementor Addons for WordPress prior to version 1.7.1070 represents a critical failure in input validation within the plugin’s form handling mechanisms. Specifically, the flaw resides in how the application processes user-submitted data when constructing email notification recipients. When an administrator configures a contact or inquiry form to dynamically set the recipient address based on submitted field values, the software fails to sanitize or validate these inputs before incorporating them into the mail header structure. This lack of validation allows unauthenticated attackers to inject arbitrary characters and addresses directly into the email headers through standard HTTP POST requests targeting the form submission endpoint.
From a technical perspective, this issue is classified as an Email Header Injection vulnerability, which aligns with CWE-93 in the Common Weakness Enumeration taxonomy. The core mechanism involves the manipulation of the To, Cc, or Bcc fields within the SMTP envelope or MIME headers. By injecting newline characters followed by additional header directives, such as CC: or BCC:, an attacker can expand the recipient list beyond what was originally intended by the site administrator. This technique exploits the way PHP’s mail function and many WordPress email libraries parse string inputs for line breaks to separate multiple recipients. Because the plugin echoes user-supplied data directly into these fields without filtering, it creates a direct path for header manipulation that bypasses standard security controls typically found in more robust form processing plugins.
The operational impact of this vulnerability is significant, primarily centering on unauthorized email relay and potential phishing campaigns. Since the emails are sent from the WordPress site’s own domain using its configured SMTP credentials or default mail server settings, they carry a high degree of trustworthiness when received by external parties. Attackers can leverage this to send malicious content that appears legitimate because it originates from a known and trusted source. This facilitates sophisticated social engineering attacks where victims are more likely to engage with the email content, click on embedded links, or open attached files under the false assumption that the communication is authorized by the website owner. Furthermore, if the injected recipients include sensitive internal addresses, there is also a risk of information leakage depending on how the application handles error responses and feedback loops during mail delivery failures.
This behavior maps directly to several techniques within the MITRE ATT&CK framework for enterprise security. It corresponds primarily to T1534, known as Internal Spearphishing, where attackers use compromised or trusted internal systems to send malicious emails that appear legitimate to targets. Additionally, it relates to T1071, Application Layer Protocol, specifically regarding SMTP abuse, and potentially T1568, Dynamic Resolution, if the attacker uses dynamic domains for hosting phishing content linked in the injected emails. The ability to relay mail from a trusted domain significantly lowers the barrier for attackers to bypass spam filters and reputation-based security systems that typically flag external sources but may allow traffic originating from internal or whitelisted IP addresses associated with legitimate web applications.
Mitigation strategies must focus on immediate remediation of the software version followed by architectural improvements in input handling. The most effective solution is to upgrade Royal Elementor Addons to version 1.7.1070 or later, where this validation flaw has been addressed by developers implementing strict allow-listing for email address formats and stripping control characters from recipient fields before processing. For organizations unable to patch immediately due to compatibility constraints, temporary mitigations include disabling the specific form feature that allows dynamic recipient selection until an update can be applied. Additionally, administrators should review their SMTP configurations to ensure that outbound mail is restricted by SPF, DKIM, and DMARC records which help detect and reject spoofed emails even if they originate from compromised infrastructure. Implementing Web Application Firewall rules that inspect HTTP POST payloads for common injection patterns such as newline characters followed by header keywords can also provide a layer of defense against exploitation attempts while the underlying code vulnerability remains unpatched in legacy systems.