CVE-2026-45118

Summary

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.

Affected Software

Weaknesses

• CWE-83: CWE-83: Improper Neutralization of Script in Attributes in a Web Page

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: total

References

• https://github.com/mybb/mybb/security/advisories/GHSA-wf92-5q5h-qr53
• https://github.com/mybb/mybb/releases/tag/mybb_1840
• https://mybb.com/versions/1.8.40

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