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)
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.002 (13.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
- Mybb — versions 1.8.26
- Mybb Forums — versions 1.8.26
Weakness classification (CWE)
References
- www.exploit-db.com/exploits/51136 (Exploit, exploit)
- mybb.com/ (Product, product)
- www.vulncheck.com/advisories/mybb-forums-stored-cross-site-scripting-via-forum-… (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.