Medium severity · published Jul 3, 2026
CVE-2026-14631
webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header
5.3
CVSS
0.5%
EPSS
No
On KEV
Description
webpack-dev-server versions 5.2.5 and earlier terminate the whole Node.js process when an unauthenticated peer sends either a normal HTTP request with a malformed Host header or a WebSocket upgrade to the default /ws endpoint with a malformed Origin header. The malformed value causes an uncaught exception in the host-validation path and crashes the dev server. Impact is limited to availability of the development server, no data disclosure, no code execution. Patches: upgrade to webpack-dev-server 5.2.6. Workarounds: keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 44% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
WE
webpack-dev-server · webpack-dev-server
before 5.2.6 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-14631
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-14631
Third Party Advisory
https://cna.openjsf.org/security-advisories.html
Mitigation
https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-m28w-2pqf-7qgj
More from webpack-dev-server
8.2
CVE-2026-112085
webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades
6.5
CVE-2026-6402
webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins
5.3
CVE-2026-114348
webpack-dev-server vulnerable to information disclosure via Host validation bypass in the open-editor endpoint
4.7
CVE-2026-14620
webpack-dev-server vulnerable to cross-site request forgery via internal developer endpoints
4.3
CVE-2026-9595
webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies