CVE-2026-14631

mediumCVSS 5.3covered by 2 sourcesfirst seen 2026-07-03

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.

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Exploitation outlook

Low exploitation risk0.52% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 42% of all EPSS-scored CVEs.

Advisory coverage (2)

mediumGHSA-m28w-2pqf-7qgj: webpack-dev-server vulnerable to denial of service via a malformed Host or Origin headerghsa · 2026-07-20
mediumCVE-2026-14631: webpack-dev-server versions 5.2.5 and earlier terminate the whole Node.js process when an unau…nvd · 2026-07-03

External references

NVD record for CVE-2026-14631

CVE.org record

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