Vulnerability in Highlightjs Highlight.js
CVE-2020-26237
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.013 (69.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 69.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000
Affected products
- Highlightjs Highlight.js — versions < 9.18.2, >= 10.0.0, < 10.1.2
- Oracle MySQL Enterprise Monitor
- Debian Linux — versions 9.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/highlightjs/highlight.js/security/advisories/GHSA-vfrc-7r7c-w9mx (Third Party Advisory, Mitigation)
- github.com/highlightjs/highlight.js/pull/2636 (Patch, Third Party Advisory)
- www.npmjs.com/package/highlight.js (Third Party Advisory)
- github.com/highlightjs/highlight.js/commit/7241013ae011a585983e176ddc0489a7a52f… (Patch, Third Party Advisory)
- lists.debian.org/debian-lts-announce/2020/12/msg00041.html (mailing-list, Mailing List, Third Party Advisory)
- www.oracle.com/security-alerts/cpujul2022.html (Third Party Advisory)
Frequently asked questions
- What is CVE-2020-26237?
- CVE-2020-26237 is a medium-severity vulnerability in Highlightjs Highlight.js, classified under Modification of Assumed-Immutable Data (MAID). CVSS score: 5.8/10. Published 2020-11-24.
- How severe is CVE-2020-26237?
- Medium severity. CVSS v3 base score is 5.8 out of 10.
- Is CVE-2020-26237 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.