CVE-2026-45125 — MyBB: Email User CRLF injection
MyBB is free and open source forum software. Prior to 1.8.40, the Email User controller does not sanitize sender names correctly, resulting in mail header injection. member.php?…
Published: 2026-08-18 · CVSS: 5.3 · CVSS 3.1
MyBB is free and open source forum software. Prior to 1.8.40, the Email User controller does not sanitize sender names correctly, resulting in mail header injection. member.php?action=do_emailuser accepts the fromname HTTP parameter for guests or the stored username for authenticated users when the cansendemail group permission is enabled. When mail_handler is set to the default PHP mail value, the sender name is used without sanitization in Return-Path and Reply-To headers, allowing arbitrary headers to be injected with CRLF sequences. This issue is fixed in version 1.8.40.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7