{"cve":"CVE-2020-26237","nvd":{"published":"2020-11-24T23:15:11.223","modified":"2026-06-17T03:07:53.420","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:H","score":8.7},"cwes":["CWE-471"],"references":["https://github.com/highlightjs/highlight.js/commit/7241013ae011a585983e176ddc0489a7a52f6bb0","https://github.com/highlightjs/highlight.js/pull/2636","https://github.com/highlightjs/highlight.js/security/advisories/GHSA-vfrc-7r7c-w9mx","https://lists.debian.org/debian-lts-announce/2020/12/msg00041.html","https://www.npmjs.com/package/highlight.js"],"products":["debian:debian_linux","highlightjs:highlight.js","oracle:mysql_enterprise_monitor"],"source":"nvd","synced_at":"2026-10-19T21:11:20.317016139+00:00"},"epss":{"cve":"CVE-2020-26237","score":0.01329,"percentile":0.71032,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-vfrc-7r7c-w9mx","url":"https://osv.dev/vulnerability/GHSA-vfrc-7r7c-w9mx","summary":"Prototype Pollution in highlight.js","modified":"2026-07-08T06:00:20.318194940Z","packages":[{"ecosystem":"npm","name":"highlight.js","purl":"pkg:npm/highlight.js","ranges":["<9.18.2"],"fixed":["9.18.2"]},{"ecosystem":"npm","name":"highlight.js","purl":"pkg:npm/highlight.js","ranges":[">=10.0.0 <10.1.2"],"fixed":["10.1.2"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}