Unauthenticated process crash via malformed header parsing
Published Jul 3, 2026 · Updated Jul 3, 2026
Denial of service in webpack-dev-server 5.2.5 and earlier allows remote attackers to crash the process via malformed Host or Origin headers. The Server class host-validation path passes each untrusted value to Node.js url.parse without catching parsing errors, so an invalid IPv6 literal raises an uncaught exception. When the development server is reachable, one unauthenticated request interrupts only that process; the default localhost binding limits remote exposure.
Summary
What happened
Denial of service in webpack-dev-server 5.2.5 and earlier allows remote attackers to crash the process via malformed Host or Origin headers. The Server class host-validation path passes each untrusted value to Node.js url.parse without catching parsing errors, so an invalid IPv6 literal raises an uncaught exception. When the development server is reachable, one unauthenticated request interrupts only that process; the default localhost binding limits remote exposure.
The record
- CVE
- CVE-2026-14631
- Published
- Jul 3, 2026
- Updated
- Jul 3, 2026
- Vendor
- webpack
- Product
- webpack-dev-server
- Classifications
- CWE-20, CWE-248, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 3, 2026CVE publishedPublication date reported by the CVE source.
- Jul 3, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <5.2.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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