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Servers and applications

CVE-2020-15139

MyCode message formatting XSS in visual editor

Severity
Medium 6.1
Published
9 Aug 2020
Last changed
17 Jun 2026
Added to UpHeron
1 Nov 2026
Fixed in
1.8.24
Also known as
GHSA-37h7-vfv6-f8rj
Sources
NVD, Project advisories (GitHub)

Description

In MyBB before version 1.8.24, the custom MyCode (BBCode) for the visual editor doesn't escape input properly when rendering HTML, resulting in a DOM-based XSS vulnerability. The weakness can be exploited by pointing a victim to a page where the visual editor is active (e.g. as a post or Private Message) and operates on a maliciously crafted MyCode message. This may occur on pages where message…

Affected software

SoftwareAffected versions
MyBBServers and applications · cpe:a:mybb:mybb
  • Every version before 1.8.24
MyBBServers and applications · github:mybb/mybb
  • Every version before 1.8.24

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2020-15139
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2020-15139
  • GitHub Advisory Database https://github.com/advisories/GHSA-37h7-vfv6-f8rj
  • github.com https://github.com/mybb/mybb/security/advisories/GHSA-37h7-vfv6-f8rj