CVE-2026-45118: critical vulnerability in mybb
MyBB: Contact page reflected XSS
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
28Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.3epss 0.5%
MyBB is free and open source forum software. Prior to 1.8.40, the Contact module does not validate a redirect URL or protocol correctly, resulting in an open redirect and reflected JavaScript code injection. contact.php accepts the redirect target from the from HTTP parameter in $mybb->input['from'] or the Referer HTTP header in $_SERVER['HTTP_REFERER'] and passes it to redirect() without sufficient verification. A javascript: URI becomes the target of the `Click here if you don't want to wait any longer` link because $force_redirect is true, allowing script execution when a victim selects the link. This issue is fixed in version 1.8.40.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Affected products
mybb · mybbRelated CVEs — mybb
In the same product, most dangerous first.
CVE-2022-24734HIGHRemote code execution in mybbEPSS 77.8%CVE-2022-39265HIGHMail settings' command parameter injection in mybbEPSS 3.1%CVE-2026-45117CRITICALMyBB: Installer database configuration RCEEPSS 1.1%CVE-2025-48940HIGHMyBB's upgrade component vulnerable to local file inclusionEPSS 0.6%CVE-2024-23335MEDIUMBackups directory .htaccess deletion in. MyBBEPSS 0.6%CVE-2026-45734MEDIUMMyBB: Default CAPTCHA missing invalidationEPSS 0.6%