CVE-2023-53978: myBB Forums 1.8.26 Stored Cross-Site Scripting via Forum Announcements

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-12-22 · updated 2026-06-17
Weakness: CWE-79

Description

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.

Affected products

mybb: 1.8.26

References

https://mybb.com/
https://www.exploit-db.com/exploits/51136
https://www.vulncheck.com/advisories/mybb-forums-stored-cross-site-scripting-via-forum-announcements

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