What is CVE-2023-53978?

CVE-2023-53978 is a medium-severity vulnerability in Mybb, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2025-12-22.

How severe is CVE-2023-53978?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Mybb

CVE-2023-53978

myBB Forums 1.8.26 contains a stored cross-site scripting vulnerability in the forum announcement system that allows authenticated administrators to inject malicious scripts when creating announcements. Attackers can exploit this vulnerability by inserting script payloads in the announcement title field when adding announcements through the 'Forums and Posts' > 'Forum Announcements' interface, causing arbitrary JavaScript to execute when the announcement is displayed on the forum.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (10.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

Affected products

Mybb — versions 1.8.26
Mybb Forums — versions 1.8.26

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

disclosure@vulncheck.com (Exploit, exploit)
disclosure@vulncheck.com (Product, product)
disclosure@vulncheck.com (Exploit, Third Party Advisory, third-party-advisory)

Frequently asked questions

What is CVE-2023-53978?: CVE-2023-53978 is a medium-severity vulnerability in Mybb, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2025-12-22.
How severe is CVE-2023-53978?: Medium severity. CVSS v3 base score is 5.4 out of 10.