Summary
Byass due to validation before canonicalization in serve
Versions of serve before 6.5.2 are vulnerable to the bypass of the ignore functionality. The bypass is possible because validation happens before canonicalization of paths and filenames.
Example:
Here we have a server that ignores the file test.txt.
const serve = require('serve')
const server = serve(__dirname, {
port: 1337,
ignore: ['test.txt']
})
Using the URL encoded form of a letter (%65 instead of e) attacker can bypass the ignore control accessing the file.
curl http://localhost:1337/t%65st.txt
Additionally this technique can be used to get directory listings of ignored directories.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Update to version 6.5.2 or later.
Frequently Asked Questions
- What is GHSA-WM7Q-RXCH-43MX? GHSA-WM7Q-RXCH-43MX is a high-severity security vulnerability in serve (npm), affecting versions < 6.5.2. It is fixed in 6.5.2.
- Which versions of serve are affected by GHSA-WM7Q-RXCH-43MX? serve (npm) versions < 6.5.2 is affected.
- Is there a fix for GHSA-WM7Q-RXCH-43MX? Yes. GHSA-WM7Q-RXCH-43MX is fixed in 6.5.2. Upgrade to this version or later.
- Is GHSA-WM7Q-RXCH-43MX exploitable, and should I be worried? Whether GHSA-WM7Q-RXCH-43MX 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
- What actually determines whether GHSA-WM7Q-RXCH-43MX 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.
- How do I fix GHSA-WM7Q-RXCH-43MX? Upgrade
serveto 6.5.2 or later.