CVE-2026-82883: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in Marcus Login With Ajax

The vulnerability identified as CVE-2026-82883 in the Marcus Login With Ajax plugin is a reflected Cross-site Scripting (CWE-79) flaw. It occurs due to improper input neutralization during web page generation, which can be exploited to execute arbitrary scripts in the context of the victim's browser. The CVSS 3.1 score is 7.1, indicating high severity with network attack vector, low attack complexity, no privileges required, user interaction required, and impacts on confidentiality, integrity, and availability. The affected versions include all versions up to 4.5.1, though exact affected versions are not explicitly listed. No known exploits in the wild or vendor advisories with patch information are currently available.

Successful exploitation of this reflected XSS vulnerability could allow an attacker to execute arbitrary scripts in the context of the affected web application, potentially leading to information disclosure, session hijacking, or other impacts on confidentiality, integrity, and availability as indicated by the CVSS vector. However, no known active exploitation has been reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should consider implementing input validation and output encoding as temporary mitigations to reduce risk from reflected XSS attacks.