Cross-Site Scripting

2019-10-0419:21:25

Michał Bentkowski

www.npmjs.com

6.1 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

4.3 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:M/Au:N/C:N/I:P/A:N

JSON

Overview

Versions of dompurify prior to 2.0.3 are vulnerable to Cross-Site Scripting (XSS). The package has an XSS filter bypass due to Mutation XSS in both Chrome and Safari through a combination of <svg>/<math> elements and </p>/</br>. An example payload is: <svg></p><style><a>. This allows attackers to bypass the XSS protection and execute arbitrary JavaScript in a victim’s browser.

Recommendation

Upgrade to version 2.0.3 or later. You may also disallow <svg> and <math> through dompurify configurations:

     FORBID_TAGS: ['svg', 'math']
 });```

## References

- [Vulnerability Report by Securitum](https://research.securitum.com/dompurify-bypass-using-mxss/)
- [GitHub Advisory](https://github.com/advisories/GHSA-chqj-j4fh-rw7m)