CVE-2020-26237
published 2020-11-24CVE-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…
PriorityP341high8.7CVSS 3.1
AVNACLPRLUIRSCCNIHAH
EPSS
1.31%
67.3th percentile
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.
Affected
13 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | debian_linux | — | — |
| debian | highlight.js | < highlight.js 9.18.1+dfsg1-3 (bookworm) | highlight.js 9.18.1+dfsg1-3 (bookworm) |
| highlightjs | highlight.js | < 9.18.2 | 9.18.2 |
| highlightjs | highlight.js | — | — |
| highlightjs | highlight.js | >= 0 < 9.18.1+dfsg1-3 | 9.18.1+dfsg1-3 |
| highlightjs | highlight.js | >= 0 < 9.18.1+dfsg1-3 | 9.18.1+dfsg1-3 |
| highlightjs | highlight.js | >= 0 < 9.18.1+dfsg1-3 | 9.18.1+dfsg1-3 |
| highlightjs | highlight.js | >= 0 < 9.18.1+dfsg1-3 | 9.18.1+dfsg1-3 |
| highlightjs | highlight.js | >= 0 < 9.18.2 | 9.18.2 |
| highlightjs | highlight.js | >= 10.0.0 < 10.1.2 | 10.1.2 |
| highlightjs | highlight.js | >= 10.1.0 < 10.1.2 | 10.1.2 |
| oracle | mysql_enterprise_monitor | <= 8.0.30 | — |
| ubuntu | highlight.js | — | — |
CVSS provenance
nvdv3.18.7HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:H
nvdv2.04.9MEDIUMAV:N/AC:M/Au:S/C:N/I:P/A:P
osv8.7HIGH
vendor_oracle6.8MEDIUM
vendor_debian5.8MEDIUM
vendor_redhat5.8MEDIUM
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OSV
CVE-2020-26237: Highlight
osv·2020-11-24·CVSS 8.7
CVE-2020-26237 [HIGH] CVE-2020-26237: Highlight
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
GHSA
Prototype Pollution in highlight.js
ghsa·2020-11-24
CVE-2020-26237 [MEDIUM] CWE-471 Prototype Pollution in highlight.js
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
OSV
Prototype Pollution in highlight.js
osv·2020-11-24
CVE-2020-26237 [MEDIUM] Prototype Pollution in highlight.js
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
Ubuntu
Highlight.js vulnerability
vendor_ubuntu·2026-05-19
CVE-2020-26237 Highlight.js vulnerability
Title: Highlight.js vulnerability
Summary: Highlight.js could be made to crash if it received specially crafted
input.
It was discovered that Highlight.js used plain JavaScript objects for
internal language name lookups, making them susceptible to prototype
pollution attacks. An attacker could use this to cause a denial of
service or unexpected application behaviour.
Instructions: In general, a standard system update will make all the necessary changes.
Oracle
Oracle Oracle MySQL Risk Matrix: Monitoring: General (highlight.js) — CVE-2020-26237
vendor_oracle·2022-07-15·CVSS 6.8
CVE-2020-26237 [MEDIUM] Oracle Oracle MySQL Risk Matrix: Monitoring: General (highlight.js) — CVE-2020-26237
Oracle Oracle MySQL Risk Matrix: Monitoring: General (highlight.js) vulnerability
CVE: CVE-2020-26237
CVSS: 6.8
Protocol: Multiple
Remote exploit: No
Affected versions: Network
Advisory: cpujul2022 (JUL 2022)
Red Hat
nodejs-highlight-js: prototype pollution via a crafted HTML code block
vendor_redhat·2020-11-23·CVSS 5.8
CVE-2020-26237 [MEDIUM] CWE-20 nodejs-highlight-js: prototype pollution via a crafted HTML code block
nodejs-highlight-js: prototype pollution via a crafted HTML code block
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 d
Debian
CVE-2020-26237: highlight.js - Highlight.js is a syntax highlighter written in JavaScript. Highlight.js version...
vendor_debian·2020·CVSS 5.8
CVE-2020-26237 [MEDIUM] CVE-2020-26237: highlight.js - Highlight.js is a syntax highlighter written in JavaScript. Highlight.js version...
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
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://github.com/highlightjs/highlight.js/commit/7241013ae011a585983e176ddc0489a7a52f6bb0https://github.com/highlightjs/highlight.js/pull/2636https://github.com/highlightjs/highlight.js/security/advisories/GHSA-vfrc-7r7c-w9mxhttps://lists.debian.org/debian-lts-announce/2020/12/msg00041.htmlhttps://www.npmjs.com/package/highlight.jshttps://www.oracle.com/security-alerts/cpujul2022.htmlhttps://github.com/highlightjs/highlight.js/commit/7241013ae011a585983e176ddc0489a7a52f6bb0https://github.com/highlightjs/highlight.js/pull/2636https://github.com/highlightjs/highlight.js/security/advisories/GHSA-vfrc-7r7c-w9mxhttps://lists.debian.org/debian-lts-announce/2020/12/msg00041.htmlhttps://www.npmjs.com/package/highlight.jshttps://www.oracle.com/security-alerts/cpujul2022.html
2020-11-24
Published