CVE-2020-36049Public exploitNetwork attack vector

Service crash via attachment-count string concatenation

Published Jan 7, 2021 · Updated Aug 4, 2024

Resource exhaustion in socket.io-parser before 3.3.2 and version 3.4.0 allows remote attackers to crash Node.js services with a large packet. The decodeString function appends each character of an attacker-controlled attachment count into chained V8 ConsOneByteString objects before converting the resulting integer to a Number. An unauthenticated client that can reach the HTTP long-polling endpoint can exhaust the Node.js heap and terminate the hosting process with a single large POST request.

CVSS severity7.5
High
EPSS probability2.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in socket.io-parser before 3.3.2 and version 3.4.0 allows remote attackers to crash Node.js services with a large packet. The decodeString function appends each character of an attacker-controlled attachment count into chained V8 ConsOneByteString objects before converting the resulting integer to a Number. An unauthenticated client that can reach the HTTP long-polling endpoint can exhaust the Node.js heap and terminate the hosting process with a single large POST request.

The record

CVE
CVE-2020-36049
Published
Jan 7, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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