CVE-2020-26237
Prototype Pollution in highlight.js
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Timeline
ID reserved
By GitHub_M
- 54 days later
· 54 days later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium5.8 | CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:N |
| NVDNVD · Modified | 3.1 | High8.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:H |
- EPSS (exploitation in 30 days)
- 1.3% · top 29% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.8.
Weakness
Affected products
- affected < 9.18.2
- affected >= 10.0.0, < 10.1.2
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- npmhighlight.jsGHSA-vfrc-7r7c-w9mx (opens in a new tab)
References (6)
- https://github.com/highlightjs/highlight.js/security/advisories/GHSA-vfrc-7r7c-w9mx (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/highlightjs/highlight.js/pull/2636 (opens in a new tab)x_refsource_MISCx_transferred
- https://www.npmjs.com/package/highlight.js (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/highlightjs/highlight.js/commit/7241013ae011a585983e176ddc0489a7a52f6bb0 (opens in a new tab)x_refsource_MISCx_transferred
- [debian-lts-announce] 20201230 [SECURITY] [DLA 2511-1] highlight.js security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- https://www.oracle.com/security-alerts/cpujul2022.html (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-vfrc-7r7c-w9mx (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2020-26237)Record last updated .