CVE-2020-26237 – highlight.js

Package

Manager: npm
Name: highlight.js
Vulnerable Version: >=0 <9.18.2 || >=10.0.0 <10.1.2

Severity

Level: Medium

CVSS v3.1: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:N

CVSS v4.0: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS: 0.00422 pctl0.61262

Details

Prototype Pollution in highlight.js ### Impact Affected versions of this package are vulnerable to Prototype Pollution. A malicious HTML code block can be crafted that will result in prototype pollution of the base object's prototype during highlighting. If you allow users to insert custom HTML code blocks into your page/app via parsing Markdown code blocks (or similar) and do not filter the language names the user can provide you may be vulnerable. The pollution should just be harmless data but this can cause problems for applications not expecting these properties to exist and can result in strange behavior or application crashes, i.e. a potential DOS vector. _If your website or application does not render user provided data it should be unaffected._ ### Patches Versions 9.18.2 and 10.1.2 and newer include fixes for this vulnerability. If you are using version 7 or 8 you are encouraged to upgrade to a newer release. ### Workarounds #### Patch your library Manually patch your library to create null objects for both `languages` and `aliases`: ```js const HLJS = function(hljs) { // ... var languages = Object.create(null); var aliases = Object.create(null); ``` #### Filter out bad data from end users: Filter the language names that users are allowed to inject into your HTML to guarantee they are valid. ### References * [What is Prototype Pollution?](https://codeburst.io/what-is-prototype-pollution-49482fc4b638) * https://github.com/highlightjs/highlight.js/pull/2636 ### For more information If you have any questions or comments about this advisory: * Please file an issue against [highlight.js](https://github.com/highlightjs/highlight.js/issues/)

Metadata

Created: 2020-11-24T22:58:41Z
Modified: 2022-10-20T13:52:50Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2020/11/GHSA-vfrc-7r7c-w9mx/GHSA-vfrc-7r7c-w9mx.json
CWE IDs: ["CWE-471"]
Alternative ID: GHSA-vfrc-7r7c-w9mx
Finding: F138
Auto approve: 1