GHSA-vfrc-7r7c-w9mx

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Source
https://github.com/advisories/GHSA-vfrc-7r7c-w9mx
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2020/11/GHSA-vfrc-7r7c-w9mx/GHSA-vfrc-7r7c-w9mx.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-vfrc-7r7c-w9mx
Aliases
Related
Published
2020-11-24T22:58:41Z
Modified
2026-03-13T22:00:13.125055Z
Severity
  • 5.8 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:N CVSS Calculator
Summary
Prototype Pollution in highlight.js
Details

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 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.

Workarounds

Patch your library

Manually patch your library to create null objects for both languages and aliases:

const HLJS = function(hljs) {
  // ...
  var languages = Object.create(null);
  var aliases = Object.create(null);

Filter out bad data from end users:

Filter the language names that users are allowed to inject into your HTML to guarantee they are valid.

References

For more information

If you have any questions or comments about this advisory:

Database specific 
{
    "nvd_published_at": "2020-11-24T23:15:00Z",
    "severity": "MODERATE",
    "cwe_ids": [
        "CWE-471"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2020-11-24T22:56:50Z"
}
References

Affected packages

npm / highlight.js

Package

Name
highlight.js
View open source insights on deps.dev
Purl
pkg:npm/highlight.js

Affected ranges

Type
SEMVER
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
9.18.2

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2020/11/GHSA-vfrc-7r7c-w9mx/GHSA-vfrc-7r7c-w9mx.json"

npm / highlight.js

Package

Name
highlight.js
View open source insights on deps.dev
Purl
pkg:npm/highlight.js

Affected ranges

Type
SEMVER
Events
Introduced
10.0.0
Fixed
10.1.2

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2020/11/GHSA-vfrc-7r7c-w9mx/GHSA-vfrc-7r7c-w9mx.json"