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GHSA-m28w-2pqf-7qgj

MediumCVSS 5.3 / 10
Published Jul 20, 2026·Last modified Jul 20, 2026
Affected Components(0)

No affected components available

Description

Impact

An unauthenticated peer that can reach the webpack-dev-server process can terminate it by sending 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 header triggers an uncaught exception in the host-validation path and crashes the dev server process.

Patches

Fixed in webpack-dev-server 5.2.6 by treating malformed Host and Origin header values as invalid rather than throwing (see PR #5699).

Workarounds

Keep the dev server bound to localhost (the default) and do not expose it to untrusted networks.

Risk Scores
Base Score
5.3

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the availability of the system.

Threat Intelligence
4.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.40%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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