What is CVE-2023-53977?

CVE-2023-53977 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-2023-53977?

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

XSS in Mybb

CVE-2023-53977

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

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-2023-53977?: CVE-2023-53977 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-2023-53977?: Medium severity. CVSS v3 base score is 5.4 out of 10.