CVE-2020-26237 Prototype Pollution in highlight.js
Prototype pollution in highlight.js allows attackers to cause denial of service via malicious HTML code blocks if user input is rendered.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2020-26237?
CVE-2020-26237 is a medium-severity vulnerability in Debian Debian Linux, published on 24 Nov 2020. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Highlight.js is a syntax highlighter written in JavaScript. Highlight.js versions before 9.18.2 and 10.1.2 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. 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.
Weakness: CWE-471
Which versions are affected by CVE-2020-26237?
4 open source packages ship an affected version, including highlight.js. It affects 3 products.
| Package | Affected | Fixed in |
|---|---|---|
highlight.js npm | All versions | 9.18.2 |
highlight.js npm | All versions | 9.18.2 |
highlight.js npm | From 10.0.0 | 10.1.2 |
highlight.js npm | From 10.0.0 | 10.1.2 |
Products include Debian Debian Linux, Highlightjs Highlight.js, Oracle Mysql Enterprise Monitor.
How do I fix CVE-2020-26237?
Upgrade highlight.js to a fixed version for your release line: 9.18.2 or 10.1.2.
Is CVE-2020-26237 being exploited?
There is no known exploitation of CVE-2020-26237 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as CLSA-2026-1788553382, DEBIAN-CVE-2020-26237, DLA-2511-1, GHSA-vfrc-7r7c-w9mx, UBUNTU-CVE-2020-26237, USN-8276-1.