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.
Does this matter?
Lower severity and a low EPSS score (1.32%). Track it; it rarely justifies an emergency change on its own.
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 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.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 1.32% probability · 69th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- mybb/mybb
- Source
- security-advisories@github.com
References
- https://github.com/mybb/mybb/commit/37ad29dcd25489a37bdd89ebac761f22492558b0Patch, Third Party Advisory
- https://github.com/mybb/mybb/security/advisories/GHSA-37h7-vfv6-f8rjPatch, Third Party Advisory
- https://mybb.com/versions/1.8.24/Patch, Vendor Advisory
- https://github.com/mybb/mybb/commit/37ad29dcd25489a37bdd89ebac761f22492558b0Patch, Third Party Advisory
- https://github.com/mybb/mybb/security/advisories/GHSA-37h7-vfv6-f8rjPatch, Third Party Advisory
- https://mybb.com/versions/1.8.24/Patch, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.