CVE-2016-9421

6.1 mediumEPSS 1.3%

Medium (6.1) in mybb. EPSS 1.3% chance of exploitation in the next 30 days.

Cross-site scripting (XSS) vulnerability in the Users module in the Admin control panel in MyBB (aka MyBulletinBoard) before 1.8.8 and MyBB Merge System before 1.8.8 might allow remote attackers to inject arbitrary web script or HTML via unspecified vectors.

Severity

CVSS 3.0

6.1 medium

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS: 1.3% chance of exploitation in the next 30 days; higher than 69% of CVEs (scores of 2026-10-31)
CWE: CWE-79
Published: 2017-01-31
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mybb:merge_system
mybb:mybb

References

http://www.openwall.com/lists/oss-security/2016/11/10/8
http://www.openwall.com/lists/oss-security/2016/11/18/1
http://www.securityfocus.com/bid/94396
https://blog.mybb.com/2016/10/17/mybb-1-8-8-merge-system-1-8-8-release/
http://www.openwall.com/lists/oss-security/2016/11/10/8

Check your stack JSON