CVE-2026-45118
MyBB: Contact page reflected XSS
- State
- Published
- Severity
- 9.3 Critical
- Published
- Aug 18, 2026
- Updated
- Aug 18, 2026
- Reserved
- May 8, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.3 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N | GitHub_M |
Weaknesses
- CWE-83 Improper Neutralization of Script in Attributes in a Web Page
Affected Products
| Product | Versions |
|---|---|
mybbmybb |
|
References
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