CVE-2021-36581Network attack vector

Dangerous file placement via unchecked upload extension

Published Sep 14, 2021 · Updated Jul 9, 2026

Unrestricted file upload in Kooboo CMS 2.1.1.0 allows remote attackers to place attacker-chosen ASPX files on the server. The server-side upload logic accepts filenames with arbitrary extensions without verifying that the file type is safe, but the published record does not identify the handler or endpoint. The published network vector requires no authentication or user interaction; the record establishes dangerous file placement but does not establish execution.

CVSS severity9.8
Critical
EPSS probability1.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in Kooboo CMS 2.1.1.0 allows remote attackers to place attacker-chosen ASPX files on the server. The server-side upload logic accepts filenames with arbitrary extensions without verifying that the file type is safe, but the published record does not identify the handler or endpoint. The published network vector requires no authentication or user interaction; the record establishes dangerous file placement but does not establish execution.

The record

CVE
CVE-2021-36581
Published
Sep 14, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, CAPEC-1, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 2026Record 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 NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
CAPEC-1Accessing Functionality Not Properly Constrained by ACLs
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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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