NPM · JULY 2026 · EARLY WARNING

websocket-driver npm Package: Resource Limit Bypass via Message Compression

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.
GHSA-33PH-FCCM-39PJSeverity: HIGH

An issue has been reported in the websocket-driver npm package that may allow it to accept messages larger than the configured maximum size when used with the permessage-deflate extension. This is under investigation.

What happened

The websocket-driver npm package, when used with the permessage-deflate extension, reportedly has a vulnerability that allows it to accept messages larger than the configured maximum size. This appears to be due to the limit being checked against the size of the compressed data, not the decompressed size. As a result, applications using this package may accept larger messages than expected, potentially exceeding their intended resource usage.

To assess your exposure, check if your application uses the websocket-driver npm package with the permessage-deflate extension and if the version is less than 0.8.1. If so, it is recommended to upgrade to version 0.8.1 or later as a precaution. Consult the primary sources for more detailed information and guidance.

How 0Day mitigates this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If websocket-driver is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

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