In the Reponsive Menu (free and Pro) WordPress plugins before 4.0.4, attackers could craft a request and trick an administrator into uploading a zip archive containing malicious PHP files. The attacker could then access those files to achieve remote code execution and further infect the targeted site.
https://www.wordfence.com/blog/2021/02/multiple-vulnerabilities-patched-in-responsive-menu-plugin/
https://wpscan.com/vulnerability/efca27e0-bdb6-4497-8330-081f909d6933