REDHAT-BUG-2447143: High severity npm/undici vulnerability

Published Mar 12, 2026
·
Updated

ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the servermaxwindowbits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range servermaxwindowbits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination.

The vulnerability exists because:

The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15 The createInflateRaw() call is not wrapped in a try-catch block The resulting exception propagates up through the call stack and crashes the Node.js process

Affected Software

1 affected component
npm/undici

Event History

Mar 12, 2026
Data Sourced
via Red Hat·09:01 PM
DescriptionSeverityAffected Software
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Frequently Asked Questions

1

What is the severity of REDHAT-BUG-2447143?

The severity of REDHAT-BUG-2447143 is classified as high, rated at 7.

2

What impact does REDHAT-BUG-2447143 have?

REDHAT-BUG-2447143 can lead to a denial-of-service attack due to improper validation of the server_max_window_bits parameter.

3

How do I fix REDHAT-BUG-2447143?

To fix REDHAT-BUG-2447143, you should update the undici WebSocket client to the latest version where the vulnerability is addressed.

4

Which software is affected by REDHAT-BUG-2447143?

The software affected by REDHAT-BUG-2447143 is the npm/undici WebSocket client.

5

When was REDHAT-BUG-2447143 published?

REDHAT-BUG-2447143 was published on March 12, 2026.

Contact

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