CVE-2014-6393

No Charset in Content-Type Header in express

Vulnerable versions of express do not specify a charset field in the content-type header while displaying 400 level response messages. The lack of enforcing user's browser to set correct charset, could be leveraged by an attacker to perform a cross-site scripting attack, using non-standard encodings, like UTF-7.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2014-6393 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.11.0, 4.5.0); upgrading removes the vulnerable code path.

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For express 3.x, update express to version 3.11 or later.
For express 4.x, update express to version 4.5 or later.

1. What is CVE-2014-6393? CVE-2014-6393 is a medium-severity cross-site scripting (XSS) vulnerability in express (npm), affecting versions < 3.11.0. It is fixed in 3.11.0, 4.5.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2014-6393? CVE-2014-6393 has a CVSS score of 6.1 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of express are affected by CVE-2014-6393? express (npm) versions < 3.11.0 is affected.
4. Is there a fix for CVE-2014-6393? Yes. CVE-2014-6393 is fixed in 3.11.0, 4.5.0. Upgrade to this version or later.
5. Is CVE-2014-6393 exploitable, and should I be worried? Whether CVE-2014-6393 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2014-6393 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2014-6393?
   • Upgrade express to 3.11.0 or later
   • Upgrade express to 4.5.0 or later

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