MyBB: Contact page reflected XSS

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-45118
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-18 16:17:06 UTC
Updated2026-09-08 21:02:26 UTC
DescriptionMyBB 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.

Risk And Classification

Primary CVSS: v3.1 9.3 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

EPSS: 0.003840000 probability, percentile 0.315850000 (date 2026-09-08)

Problem Types: CWE-83 | CWE-83 CWE-83: Improper Neutralization of Script in Attributes in a Web Page

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.3CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
3.1CNADECLARED9.3CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mybb Mybb affected < 1.8.40 Not specified

References

ReferenceSourceLinkTags
github.com/mybb/mybb/releases/tag/mybb_1840 [email protected] github.com
mybb.com/versions/1.8.40 [email protected] mybb.com
github.com/mybb/mybb/security/advisories/GHSA-wf92-5q5h-qr53 [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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