CVE-2020-15139

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 content is pre-filled using a GET/POST parameter, or on reply pages where a previously saved malicious message is quoted. After upgrading MyBB to 1.8.24, make sure to update the version attribute in the `codebuttons` template for non-default themes to serve the latest version of the patched `jscripts/bbcodes_sceditor.js` file.

• CVE ID
• CVE-2020-15139

• Assigner
• security-advisories@github.com

• Vulnerability Status
• Analyzed

• Published Version
• 2020-08-10T22:15:14

• Last Modified Date
• 2020-08-13T15:58:27

• Version
• 2.0

• Vector String
• AV:N/AC:M/Au:N/C:N/I:P/A:N

• Access Vector
• NETWORK

• Access Compatibility
• MEDIUM

• Authentication
• NONE

• Confidentiality Impact
• NONE

• Integrity Impact
• PARTIAL

• Availability Impact
• NONE

• Base Score
• 4.3

• Severity
• MEDIUM

• Exploitability Score
• 8.6

• Impact Score
• 2.9

• Version
• 3.1

• Vector String
• CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

• Attack Vector
• NETWORK

• Attack Compatibility
• LOW

• Privileges Required
• NONE

• User Interaction
• REQUIRED

• Scope
• CHANGED

• Confidentiality Impact
• LOW

• Availability Impact
• NONE

• Base Score
• 6.1

• Base Severity
• MEDIUM

• Exploitability Score
• 2.8

• Impact Score
• 2.7