What’s Vulnerable › Vulnerabilities

CVE-2020-36048

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-01-08 · updated 2026-06-17
• Weakness: CWE-400

Description

Engine.IO before 4.0.0 allows attackers to cause a denial of service (resource consumption) via a POST request to the long polling transport.

Affected products

• socketio engine.io: before 4.0.0 — fixed in 4.0.0

How to fix

Upgrade to a fixed version: socketio engine.io 4.0.0. Check the vendor advisory for mitigations.

References

• https://blog.caller.xyz/socketio-engineio-dos/
• https://github.com/bcaller/kill-engine-io
• https://github.com/socketio/engine.io/commit/734f9d1268840722c41219e69eb58318e0b2ac6b
• https://blog.caller.xyz/socketio-engineio-dos/
• https://github.com/bcaller/kill-engine-io
• https://github.com/socketio/engine.io/commit/734f9d1268840722c41219e69eb58318e0b2ac6b

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