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Socket.IO: Engine.IO Polling Transport Connection Exhaustion

Type: advisorySource: Official CVE List1 source record

Socket.IO enables bidirectional and low-latency communication for every platform. From 4.1.0 before 6.6.7, Engine.IO protocol v4 polling transport does not properly close the HTTP response for invalid binary POST requests with Content-Type: application/octet-stream, allowing an unauthenticated attacker to exhaust server-side connections and sockets. This issue is fixed in version 6.6.7.

Announced Source revision 1
Original source ↗

CVE-2026-59725

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-59725

engine.io

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "vendor": "socketio",
    "product": "engine.io",
    "versions": [
      {
        "status": "affected",
        "version": ">= 4.1.0, < 6.6.7"
      }
    ]
  }
]
Related CVEs
CVE-2026-59725

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#22995 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement