webpack-dev-server up to 5.2.5 WebSocket Upgrade denial of service

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.2$0-$5k1.46+

Summaryinfo

A vulnerability was found in webpack-dev-server up to 5.2.5. It has been rated as problematic. This vulnerability affects unknown code of the component WebSocket Upgrade Handler. This manipulation causes denial of service. The identification of this vulnerability is CVE-2026-14631. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in webpack-dev-server up to 5.2.5 and classified as problematic. Affected by this vulnerability is an unknown function of the component WebSocket Upgrade Handler. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

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.

The weakness was shared by UlisesGascon. It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-14631 since 07/03/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 5.2.6 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-41559). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.2

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 5.3
CNA Vector (openjs): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: webpack-dev-server 5.2.6

Timelineinfo

07/03/2026 Advisory disclosed
07/03/2026 +0 days CVE reserved
07/03/2026 +0 days VulDB entry created
07/03/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Researcher: UlisesGascon
Status: Confirmed

CVE: CVE-2026-14631 (🔒)
GCVE (CVE): GCVE-0-2026-14631
GCVE (VulDB): GCVE-100-376159
EUVD: 🔒

Entryinfo

Created: 07/03/2026 20:30
Updated: 07/03/2026 22:31
Changes: 07/03/2026 20:30 (64), 07/03/2026 22:31 (1)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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