Vulnerability Details CVE-2026-59725
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 27.7%
CVSS Severity
CVSS v3 Score 7.5
References
Products affected by CVE-2026-59725
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cpe:2.3:a:socket:engine.io:4.1.0
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cpe:2.3:a:socket:engine.io:4.1.1
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cpe:2.3:a:socket:engine.io:4.1.2
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cpe:2.3:a:socket:engine.io:5.0.0
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cpe:2.3:a:socket:engine.io:5.1.0
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cpe:2.3:a:socket:engine.io:5.1.1
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cpe:2.3:a:socket:engine.io:5.2.0
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cpe:2.3:a:socket:engine.io:5.2.1
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cpe:2.3:a:socket:engine.io:6.0.0
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cpe:2.3:a:socket:engine.io:6.0.1
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cpe:2.3:a:socket:engine.io:6.1.0
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cpe:2.3:a:socket:engine.io:6.1.1
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cpe:2.3:a:socket:engine.io:6.1.2
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cpe:2.3:a:socket:engine.io:6.1.3
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cpe:2.3:a:socket:engine.io:6.2.0
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cpe:2.3:a:socket:engine.io:6.2.1
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cpe:2.3:a:socket:engine.io:6.3.0
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cpe:2.3:a:socket:engine.io:6.3.1
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cpe:2.3:a:socket:engine.io:6.4.0
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cpe:2.3:a:socket:engine.io:6.4.1
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cpe:2.3:a:socket:engine.io:6.4.2
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cpe:2.3:a:socket:engine.io:6.5.0
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cpe:2.3:a:socket:engine.io:6.5.1
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cpe:2.3:a:socket:engine.io:6.5.2
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cpe:2.3:a:socket:engine.io:6.5.3
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cpe:2.3:a:socket:engine.io:6.5.4
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cpe:2.3:a:socket:engine.io:6.5.5
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cpe:2.3:a:socket:engine.io:6.6.0
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cpe:2.3:a:socket:engine.io:6.6.1
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cpe:2.3:a:socket:engine.io:6.6.2
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cpe:2.3:a:socket:engine.io:6.6.3
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cpe:2.3:a:socket:engine.io:6.6.4
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cpe:2.3:a:socket:engine.io:6.6.5
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cpe:2.3:a:socket:engine.io:6.6.6