CVE-2026-1947 is an authorization bypass vulnerability classified under CWE-639 (Authorization Bypass Through User-Controlled Key) affecting the NEX-Forms – Ultimate Forms Plugin for WordPress, versions up to and including 9.1.9. The vulnerability exists in the submit_nex_form() function, where the plugin fails to properly validate the 'nf_set_entry_update_id' parameter, which is user-controlled. This lack of validation enables unauthenticated attackers to perform Insecure Direct Object Reference (IDOR) attacks by manipulating this parameter to overwrite arbitrary form entries. Because the vulnerability does not require authentication or user interaction, it can be exploited remotely over the network with low attack complexity. The impact is primarily on data integrity, as attackers can alter form submission data, potentially leading to misinformation, data corruption, or manipulation of form-based workflows. The CVSS v3.1 base score is 7.5, reflecting high severity due to network attack vector, no privileges required, no user interaction, and a significant impact on integrity. No patches or fixes have been published at the time of disclosure, and no known exploits have been observed in the wild. The vulnerability affects all versions of the plugin up to 9.1.9, which is widely used in WordPress environments for form management.

The vulnerability allows unauthenticated attackers to overwrite arbitrary form entries, compromising the integrity of data collected via the NEX-Forms plugin. This can lead to misinformation, fraudulent submissions, or disruption of business processes relying on form data. Organizations that depend on accurate form data for customer interactions, registrations, or transactional workflows may face operational disruptions or reputational damage. Since the exploit requires no authentication or user interaction, the attack surface is broad, increasing the likelihood of exploitation once public awareness grows. Although availability and confidentiality are not directly impacted, the integrity breach can cascade into broader security and compliance issues, especially for organizations subject to data accuracy regulations. The lack of patches increases exposure time, and attackers could use this vulnerability to manipulate form data for fraud, misinformation campaigns, or to bypass business logic controls embedded in form workflows.

1. Immediately disable the NEX-Forms – Ultimate Forms Plugin until a security patch is released. 2. Restrict access to form submission endpoints via web application firewalls (WAFs) or IP whitelisting to limit exposure to untrusted sources. 3. Implement strict input validation and parameter filtering at the web server or application firewall level to block unauthorized manipulation of the 'nf_set_entry_update_id' parameter. 4. Monitor web server and application logs for unusual POST requests targeting form submission endpoints, especially those containing the vulnerable parameter. 5. If disabling the plugin is not feasible, consider deploying a custom patch or temporary code fix that validates the 'nf_set_entry_update_id' parameter against authorized user sessions or known entry IDs. 6. Educate site administrators to update the plugin promptly once an official patch is available and to follow secure plugin management best practices. 7. Conduct a review of form data integrity and audit recent submissions for signs of unauthorized modification. 8. Employ multi-factor authentication and least privilege principles for WordPress admin accounts to reduce the risk of further exploitation.