CVE-2020-28481Public exploitNetwork attack vector

Cross-origin data exposure via wildcard origin trust

Published Jan 19, 2021 · Updated Sep 16, 2024

CORS misconfiguration in Socket.IO before 2.4.0 allows remote attackers to read authenticated responses through a victim's browser. The Server constructor initializes origins to ':', and checkRequest accepts every supplied Origin, causing credentialed CORS headers to authorize untrusted sites. Exploitation requires a user with an active session to visit attacker-controlled content; exposed data depends on the hosting application's Socket.IO events.

CVSS severity5.3
Medium
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CORS misconfiguration in Socket.IO before 2.4.0 allows remote attackers to read authenticated responses through a victim's browser. The Server constructor initializes origins to ':', and checkRequest accepts every supplied Origin, causing credentialed CORS headers to authorize untrusted sites. Exploitation requires a user with an active session to visit attacker-controlled content; exposed data depends on the hosting application's Socket.IO events.

The record

CVE
CVE-2020-28481
Published
Jan 19, 2021
Updated
Sep 16, 2024
Vendor
Socket.IO
Product
Socket.IO
Classifications
CWE-453, CWE-346, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <2.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Socket.IO · Socket.IOversion=unspecified <2.4.0

Published CVSS scores

4.0NVDAV:N/AC:L/Au:S/C:P/I:N/A:N
4.3NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
5.3SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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-453Insecure Default Variable Initialization
CWE-346Origin Validation Error
T1190Exploit Public-Facing Application

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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