Vulnerability library
Security checkAugust 31, 2026

Socket.IO: Engine.IO WebTransport SID DoS

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High severitynpmengine.io

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Description

Engine.IO servers with WebTransport enabled are vulnerable to a remotely triggerable denial of service.

A malicious unauthenticated client can send a crafted WebTransport upgrade request containing a specially chosen session ID, such as __proto__.

Recommendation

Update the engine.io package to the latest compatible version. Followings are version details:

  • Affected version(s): >= 6.5.0, < 6.6.7
  • Patched version(s): 6.6.7

References

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See something that needs correcting? Let us knowUpdated August 31, 2026