CVE-2023-51540: 
WordPress vulnerability analysis and mitigation

A Stored Cross-Site Scripting (XSS) vulnerability was discovered in the WordPress Custom 404 Pro plugin, identified as CVE-2023-51540. The vulnerability affects all versions of Custom 404 Pro through version 3.10.0, developed by Kunal Nagar. The issue was initially reported on November 29, 2023, by security researcher Kyle Sanchez and was publicly disclosed on December 27, 2023 (Patchstack).

The vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation) and has received varying CVSS severity scores. The National Vulnerability Database (NVD) assigned a CVSS v3.1 base score of 6.1 (Medium) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N, while Patchstack rated it at 7.1 (High) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L (NVD).

The vulnerability allows malicious actors to inject malicious scripts, including redirects, advertisements, and other HTML payloads into the website. These injected scripts will be executed when guests visit the affected site, potentially compromising the security of both the website and its visitors (Patchstack).

The vulnerability has been patched in version 3.10.1 of the Custom 404 Pro plugin. Website administrators are advised to update to version 3.10.1 or later immediately. Additionally, Patchstack has issued a virtual patch to mitigate this issue by blocking potential attacks until users can update to the fixed version (Patchstack).