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

Vulnerability summary

CVE-2026-114348 is a medium (CVSS 5.3) vulnerability in webpack-dev-server. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 23.3% of scored vulnerabilities.

Timeline

1. 22-10-2026
   PublishedVulnerability first disclosed.
2. 22-10-2026
   Last modifiedVulnerability information updated.

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.

• CWE-209Generation of Error Message Containing Sensitive InformationThe product generates an error message that includes sensitive information about its environment, users, or associated data.
• CWE-1289Improper Validation of Unsafe Equivalence in InputThe product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.