Severity: Medium Date: December 22, 2025 Affected: myBB Forums 1.8.26 CVE ID: CVE-2023-53977 CWE: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CVSS Score: 7.5 (Base), 6.4 (Temporal) CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N References - ExploitDB-51136 - Official myBB Software Version Page Credit: Andrey Stoykov Description: myBB Forums 1.8.26 contains a stored cross-site scripting vulnerability in the forum management system that allows authenticated administrators to inject malicious scripts when creating new forums. Attackers can exploit this vulnerability by inserting script payloads in the forum title field when adding new forums through the 'Forums and Posts' > 'Forum Management' interface, causing arbitrary JavaScript to execute when the forum listing is viewed.