CVE-2026-76844

webpack-dev-middleware vulnerable to Path Traversal via non-slash-terminated publicPath

webpack-dev-middleware resolves a request to a local file in getFilenameFromUrl. When the configured publicPath has no trailing slash (for example /assets), a request that shares that prefix without being under it (for example /assets../secret) still passes the containment check, and the .. guard does not catch it because it runs on the path before the publicPath prefix is stripped. The stripped remainder then escapes the configured output directory once joined, so an unauthenticated request can read files outside the output root. Applications serving webpack-dev-middleware (directly or via webpack-dev-server) with a publicPath that does not end in a slash are affected. A development server reachable on the network can be attacked with a single request and no victim interaction.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-76844 has a CVSS score of 7.4 (High). 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 (8.3.0, 7.4.6); upgrading removes the vulnerable code path.

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Patched in webpack-dev-middleware 8.3.0. There is no backport to the 5.x, 6.x, or 7.x lines; users on those lines should upgrade to 8.3.0 or later.

1. What is CVE-2026-76844? CVE-2026-76844 is a high-severity path traversal vulnerability in webpack-dev-middleware (npm), affecting versions >= 8.0.0, < 8.3.0. It is fixed in 8.3.0, 7.4.6. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-76844? CVE-2026-76844 has a CVSS score of 7.4 (High). 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 webpack-dev-middleware are affected by CVE-2026-76844? webpack-dev-middleware (npm) versions >= 8.0.0, < 8.3.0 is affected.
4. Is there a fix for CVE-2026-76844? Yes. CVE-2026-76844 is fixed in 8.3.0, 7.4.6. Upgrade to this version or later.
5. Is CVE-2026-76844 exploitable, and should I be worried? Whether CVE-2026-76844 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-2026-76844 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-2026-76844?
   • Upgrade webpack-dev-middleware to 8.3.0 or later
   • Upgrade webpack-dev-middleware to 7.4.6 or later

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