Media

Prototype Pollution in highlight.js

Publicada: 24.11.2020
Actualizado: 11.10.2026 10:22

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:

Please file an issue against highlight.js

Software afectado

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Plataforma	Paquete	Versiones vulnerables	Corregida en
Paquete de npm	highlight.js	< 9.18.2, >= 10.0.0, < 10.1.2	9.18.2, 10.1.2

Referencias

Puntuación CVSS 5.8/10

Vector CVSS: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:N
Debilidad (CWE): CWE-471
Plataforma: npm
Paquete: highlight.js
Publicada: 24.11.2020
Actualizado: 11.10.2026 10:22

Fuentes y licencias

OSV / GitHub Advisory Database - GHSA-vfrc-7r7c-w9mx - CC BY 4.0

Historial de vulnerabilidades: highlight.js

Todas las vulnerabilidades publicadas de este paquete (Paquete de npm), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.

Entradas en total: 2
Primera → última: 11.2020 12.2020
Sin corrección: 0
Explotada en ataques: 0

Distribución por gravedad

Media 2

Divulgaciones por año

2020: 2
2021: 0
2022: 0
2023: 0
2024: 0
2025: 0
2026: 0

04.12.2020

ReDOS vulnerabities: multiple grammars

Media ghsa-7wwv-vh3v-89cq >= 9.0.0, < 10.4.1 10.4.1
24.11.2020

Prototype Pollution in highlight.js esta entrada

Media · 5.8 CVE-2020-26237 < 9.18.2, >= 10.0.0, < 10.1.2 9.18.2, 10.1.2

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