webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Partial Red Hat: 28 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA, GitHub and Red Hat.
Summary
webpack-dev-server versions up to and including 5.2.3 are vulnerable to cross-origin source code exposure when serving over a non-potentially trustworthy origin such as plain HTTP. The previous fix relied on the Sec-Fetch-Mode and Sec-Fetch-Site request headers, which browsers omit for non-trustworthy origins, allowing a malicious site to load the bundled source as a script and read it across origins. Impact: an attacker controlling a website visited by a developer running webpack-dev-server can recover the application source code when the dev server runs over HTTP at a guessable host and port. Chromium based browsers from Chrome 142 onward are not affected due to local network access restrictions. Upgrade to webpack-dev-server 5.2.4 or later, which sets Cross-Origin-Resource-Policy: same-origin on responses.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| webpack | webpack-dev-server | before 5.2.4 | 5.2.4 | Patch available | CNA |
| — | webpack-dev-server (npm) | before 5.2.4 | 5.2.4 | Patch available | GHSA-79cf-xcqc-c78w |
- webpack-dev-server Vendorwebpack Affected before 5.2.4 Fixed in 5.2.4 Patch available CNA
- webpack-dev-server (npm) Vendor— Affected before 5.2.4 Fixed in 5.2.4 Patch available GHSA-79cf-xcqc-c78w
Remediation
- Fix · CNA webpack-dev-server (webpack-dev-server) Fixed in 5.2.4
- Fix · GHSA-79cf-xcqc-c78w webpack-dev-server (npm) Fixed in 5.2.4 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Cryostat 4 | Affected | No fix yet: Fix deferred |
| Gatekeeper 3 | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Containers | Affected | No fix yet: Fix deferred |
| Node HealthCheck Operator | Affected | No fix yet: Fix deferred |
| OpenShift Lightspeed | Affected | No fix yet: Fix deferred |
| OpenShift Pipelines | Affected | No fix yet: Fix deferred |
| OpenShift Service Mesh 2 | Affected | No fix yet: Fix deferred |
| OpenShift Service Mesh 3 | Affected | No fix yet: Fix deferred |
| Red Hat AMQ Broker 7 | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Build of Podman Desktop | Affected | No fix yet: Fix deferred |
| Red Hat Data Grid 8 | Affected | No fix yet: Fix deferred |
| Red Hat Developer Hub 1 | Affected | No fix yet: Fix deferred |
| Red Hat Discovery 2 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat Fuse 7 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Virtualization 4 | Affected | No fix yet: Fix deferred |
| Red Hat Process Automation 7 | Affected | No fix yet: Fix deferred |
| Red Hat Quay 3 | Affected | No fix yet: Fix deferred |
| Red Hat build of Apache Camel - HawtIO 4 | Affected | No fix yet: Fix deferred |
| Red Hat build of Apache Camel for Spring Boot 4 | Affected | No fix yet: Fix deferred |
| Red Hat build of Apicurio Registry 2 | Affected | No fix yet: Fix deferred |
| Self-service automation portal 2 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-6402
- 2026-10-03 Alias added: GHSA-79cf-xcqc-c78w
- 2026-10-27 Affected versions changed · Red Hat
References
Advisory 3
More Webpack-dev-server vulnerabilities
- 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-2026-79254 Host validation bypass in webpack-dev-server leaks stack traces CVSS 3.1MEDIUM 5.3
Sources
- CVE-2026-6402 · CVE Program
- CVE-2026-6402 · NVD
- FIRST EPSS
- GHSA-79cf-xcqc-c78w · GitHub Advisory Database · CC BY 4.0
- CVE-2026-6402 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences