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CVE Record

CVE-2016-10536: engine.io-client is the client for engine.io, the implementation of a transport-based cross-browser/cross-d...

engine.io-client is the client for engine.io, the implementation of a transport-based cross-browser/cross-device bi-directional communication layer for Socket.IO. The vulnerability is related to the way that node.js handles the `rejectUnauthorized` setting. If the value is something that evaluates to false, certificate verification will be disabled. This is problematic as engine.io-client 1.6.8 and earlier passes in an object for settings that includes the rejectUnauthorized property, whether it has been set or not. If the value has not been explicitly changed, it will be passed in as `null`, resulting in certificate verification being turned off.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2016-10536 can silently turn off TLS certificate checks in affected engine.io-client versions. That means a connection that appears encrypted may not verify the server identity, increasing risk of interception or impersonation when network traffic can be controlled.

Executive priority

Prioritize remediation where affected clients connect over untrusted networks, handle sensitive data, or support authentication flows. Lower urgency may apply to isolated internal use, but the default should be dependency cleanup.

Technical view

engine.io-client 1.6.8 and earlier passed a settings object containing rejectUnauthorized even when unset. The unset value could be null, which Node.js treats as disabling certificate verification. The issue maps to CWE-300 and affects TLS authentication for Node.js clients using this module.

Likely exposure

Exposure is most likely in Node.js applications, tooling, or transitive Socket.IO dependencies using engine.io-client <= 1.6.8 for TLS-protected connections.

Exploitation context

The bundle does not show KEV listing or active exploitation. Practical abuse would require an attacker able to intercept or influence network traffic between the client and server.

Researcher notes

Evidence identifies the root cause and affected version boundary, but the bundle lacks CVSS, exploit telemetry, and a clearly named fixed release. Treat the linked commit as authoritative implementation context.

Mitigation direction

  • Identify direct and transitive engine.io-client dependencies.
  • Upgrade engine.io-client beyond affected versions or to a release containing the linked fix.
  • Check Socket.IO dependency trees that may bundle engine.io-client.
  • Ensure TLS options explicitly preserve certificate verification.
  • Review vendor guidance if exact fixed version mapping is needed.

Validation and detection

  • Inspect package lockfiles for engine.io-client <= 1.6.8.
  • Confirm runtime dependency resolution in production builds.
  • Review client TLS configuration for rejectUnauthorized handling.
  • Test that invalid server certificates are rejected in controlled validation.
  • Document any legacy exception requiring continued exposure.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-300: Exact CWE lookup

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cve · low confidence lookup

CVE-2016-10536 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
HackerOneengine.io-client node module<= 1.6.8Listed
Weakness

CWE details

CWE-300

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.