# CVE-2014-6393: Express missing charset in Content-Type header XSS

Source: https://junglewise.ai/threats/cve-2014-6393-express-missing-charset-in-content-type-header-xss  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2018-10-23. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2014-6393 · Severity: low · CVSS 3 · Published 2018-10-23

Express, a popular web framework for Node.js applications, fails to specify a charset field in Content-Type headers for error responses. An attacker can exploit this omission to inject malicious scripts through non-standard character encodings (such as UTF-7), potentially compromising user sessions, stealing credentials, or redirecting users to malicious sites. This affects any website built with vulnerable versions of Express.

Technologies: [Express](https://junglewise.ai/threats/technologies/npm-express).

## Quick answers

**Is CVE-2014-6393 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2014-6393 being exploited in the wild.

**How severe is CVE-2014-6393?** Low severity, with a CVSS score of 3, published 23 October 2018.

**Which products and versions are affected?** Express SEMVER:introduced=0,fixed=3.11.0.

**Is there a fix for CVE-2014-6393?** Yes. Express: upgrade to 3.11.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2014-6393 attacked?** It is attacked over the network.

**Am I affected by CVE-2014-6393?** Check whether you run Express at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Express: upgrade to 3.11.0 or later

## Technical details

Express versions prior to 3.11 and 4.x versions prior to 4.5 do not enforce a charset in the Content-Type header when sending HTTP 400-level error responses. This allows attackers to perform stored or reflected cross-site scripting (XSS) attacks by leveraging non-standard character encodings like UTF-7 to bypass the browser's default charset interpretation. The vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation). An attacker can craft requests that trigger error responses containing JavaScript payloads encoded in UTF-7, which browsers will interpret and execute. The fix is to update Express to version 3.11 or later for the 3.x branch, or version 4.5 or later for the 4.x branch.

## Affected products

- OpenJS Foundation Express 3.x < 3.11, 4.x < 4.5

## Identifiers

- CVE-2014-6393
- GHSA-gpvr-g6gh-9mc2

## Timeline

- 2014: disclosed: Vulnerability initially discovered
- 2018-10-23: advisory: GHSA advisory published

## References

- [https://bugzilla.redhat.com/show_bug.cgi?id=1203190](https://bugzilla.redhat.com/show_bug.cgi?id=1203190)

## Related threats

- [Rejected reason: ** REJECT ** DO NOT USE THIS CANDIDATE NUMBER. Reason: This candidate was issued in error and is not a valid vulnerability.](https://junglewise.ai/threats/cve-2024-51999-express-extended-query-parser-prototype-pollution)
- [Express resource injection in Link header](https://junglewise.ai/threats/cve-2024-10491-express-resource-injection-in-link-header)
- [Express open redirect vulnerability](https://junglewise.ai/threats/cve-2024-9266-express-open-redirect-vulnerability)
- [Express XSS via response.redirect()](https://junglewise.ai/threats/cve-2024-43796-express-xss-via-response-redirect)
- [Express.js open redirect in malformed URLs](https://junglewise.ai/threats/cve-2024-29041-express-js-open-redirect-in-malformed-urls)