Client memory exhaustion via unlimited WebSocket fragments
Published Jun 17, 2026 · Updated Jun 17, 2026
Denial of service in the Undici WebSocket client allows remote attackers controlling a WebSocket server to exhaust client memory. The receiver checks cumulative payload bytes but does not limit fragment count, so numerous tiny or empty continuation frames consume unbounded wrapper memory. Exposure requires WebSocket or WebSocketStream code to connect to an attacker-controlled or compromised endpoint, where exhaustion crashes the client process.
Summary
What happened
Denial of service in the Undici WebSocket client allows remote attackers controlling a WebSocket server to exhaust client memory. The receiver checks cumulative payload bytes but does not limit fragment count, so numerous tiny or empty continuation frames consume unbounded wrapper memory. Exposure requires WebSocket or WebSocketStream code to connect to an attacker-controlled or compromised endpoint, where exhaustion crashes the client process.
The record
- CVE
- CVE-2026-12151
- Published
- Jun 17, 2026
- Updated
- Jun 17, 2026
- Vendor
- Node.js
- Product
- Undici
- Classifications
- CWE-770, CWE-400, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 17, 2026CVE publishedPublication date reported by the CVE source.
- Jun 17, 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 <6.26.0
- Affected versionversion=7.0.0 <7.28.0
- Affected versionversion=8.0.0 <8.5.0
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
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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