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TI-2026-79254 Aliases CVE-2026-114348

Host validation bypass in webpack-dev-server leaks stack traces

Priority LOW 30CWE-1289Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-209.

Summary

webpack-dev-server from 5.1.0 before 5.2.7 and from 6.0.0 before 6.1.0 is affected. The unauthenticated open-editor endpoint validates the Host header with a regular expression meant for browser Origin schemes, so a Host starting with file: or an extension scheme skips the hostname and allowedHosts checks. A network peer can send a malformed Host that makes URL construction throw, and the default non-production HTTP 500 response then includes the full stack trace, exposing filesystem paths and source line numbers (CWE-209).

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00305 23rd percentileScored 2026-11-07
Fix Fixed webpack-dev-server (webpack-dev-server): 5.2.7, 6.1.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
webpackwebpack-dev-server5.1.0 to before 5.2.7; 6.0.0 to before 6.1.05.2.7, 6.1.0Patch availableCNA
  • webpack-dev-server Vendorwebpack Affected 5.1.0 to before 5.2.7; 6.0.0 to before 6.1.0 Fixed in 5.2.7, 6.1.0 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:webpack.js:webpack-dev-server:*:*:*:*:*:*:*:*5.1.0 to before 5.2.7; 6.0.0 to before 6.1.0Vulnerablewebpack
  • cpe:2.3:a:webpack.js:webpack-dev-server:*:*:*:*:*:*:*:* Versions 5.1.0 to before 5.2.7; 6.0.0 to before 6.1.0 Vulnerable ·webpack

Remediation

Upgrade to webpack-dev-server 5.2.7 for the 5.x branch or to 6.1.0 for the 6.x branch.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

  • Fix · CNA webpack-dev-server (webpack-dev-server) Fixed in 5.2.7, 6.1.0

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    webpack-dev-server 5.2.7, 6.1.0

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2026-79248 Missing Origin checks on proxied WebSockets in webpack-dev-serverPriority LOW 35
    Show all 2 records →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat Hardened Images

Timeline

  1. 2026-10-22 Threatist record created from CVE-2026-114348
  2. 2026-10-22 CISA SSVC decision points changed
  3. 2026-10-23 Affected versions changed · Red Hat
  4. 2026-10-23 CVSS score added · Red Hat

References

Advisory 2

  • TI-2025-21666 Origin validation error in webpack-dev-server CVSS 3.1MEDIUM 6.5
  • TI-2025-21665 webpack-dev-server users' source code may be stolen when they access a malicious web site CVSS 3.1MEDIUM 5.9
  • TI-2018-10580 An issue was discovered in lib/Server.js in webpack-dev-server before 3.1.6. CVSS 3.0HIGH 7.5
  • TI-2026-79248 Missing Origin checks on proxied WebSockets in webpack-dev-server CVSS 3.1HIGH 8.2
  • TI-2026-12328 webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header CVSS 3.1MEDIUM 5.3
  • TI-2026-08430 webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies CVSS 3.1MEDIUM 5.3
See all 8 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences