Critical RCE Flaw Reported in MyBB Forum Software—Patch Your Sites
Mar 18, 2021
A pair of critical vulnerabilities in a popular bulletin board software called MyBB could have been chained together to achieve remote code execution (RCE) without the need for prior access to a privileged account. The flaws, which were discovered by independent security researchers Simon Scannell and Carl Smith, were reported to the MyBB Team on February 22, following which it released an update (version 1.8.26) on March 10 addressing the issues. MyBB, formerly MyBBoard and originally MyBulletinBoard, is free and open-source forum software developed using PHP and MySQL. According to internet assets search engine Spyse, there are at least 2,100 potentially vulnerable domains that have MyBB installed. According to the researchers, the first issue — a nested auto URL persistent XSS vulnerability (CVE-2021-27889) — stems from how MyBB parses messages containing URLs during the rendering process, thus enabling any unprivileged forum user to embed stored XSS payloads into t...
