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CVE-2026-102599GHSA-2GC4-CQFQ-P2GV

Socket.IO: Engine.IO Protocol Revision Mismatch DoS

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 6.6.10
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

Summary

Socket.IO enables bidirectional and low-latency communication for every platform. From Engine.IO 6.6.0 until 6.6.10, a transport upgrade can independently derive an Engine.IO protocol revision from the upgrade request instead of enforcing the revision stored on the existing session. A malicious client can establish a valid session and send an upgrade request with a different or omitted EIO query parameter, attaching a transport with incompatible parser and heartbeat behavior. A crafted heartbeat packet can then trigger an uncaught exception and terminate the Node.js process, including when Engine.IO v3 compatibility is disabled because an omitted EIO value is interpreted as revision 3 on the affected path. This issue is fixed in Engine.IO 6.6.10.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • socketio socket.io

    From 6.6.0 · fixed in 6.6.10

  • engine.ionpm

    From 6.6.0 · fixed in 6.6.10

References 3

GitHub · socketio/socket.io