The undici WebSocket client is vulnerable to a denial-of-service attack via unbounded memory consumption during permessage-deflate decompression. When a WebSocket connection negotiates the permessage-deflate extension, the client decompresses incoming compressed frames without enforcing any limit on the decompressed data size. A malicious WebSocket server can send a small compressed frame (a "decompression bomb") that expands to an extremely large size in memory, causing the Node.js process to exhaust available memory and crash or become unresponsive.
The vulnerability exists in the PerMessageDeflate.decompress() method, which accumulates all decompressed chunks in memory and concatenates them into a single Buffer without checking whether the total size exceeds a safe threshold.
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History
Fri, 13 Mar 2026 00:15:00 +0000
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| Weaknesses | CWE-770 | |
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threat_severity
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threat_severity
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Thu, 12 Mar 2026 20:30:00 +0000
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| Description | The undici WebSocket client is vulnerable to a denial-of-service attack via unbounded memory consumption during permessage-deflate decompression. When a WebSocket connection negotiates the permessage-deflate extension, the client decompresses incoming compressed frames without enforcing any limit on the decompressed data size. A malicious WebSocket server can send a small compressed frame (a "decompression bomb") that expands to an extremely large size in memory, causing the Node.js process to exhaust available memory and crash or become unresponsive. The vulnerability exists in the PerMessageDeflate.decompress() method, which accumulates all decompressed chunks in memory and concatenates them into a single Buffer without checking whether the total size exceeds a safe threshold. | |
| Title | undici is vulnerable to Unbounded Memory Consumption in undici WebSocket permessage-deflate Decompression | |
| Weaknesses | CWE-409 | |
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cvssV3_1
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Status: PUBLISHED
Assigner: openjs
Published:
Updated: 2026-03-12T20:08:05.950Z
Reserved: 2026-01-28T12:05:07.017Z
Link: CVE-2026-1526
No data.
Status : Received
Published: 2026-03-12T21:16:23.933
Modified: 2026-03-12T21:16:23.933
Link: CVE-2026-1526
OpenCVE Enrichment
No data.