CVE-2020-21489Public exploitNetwork attack vector

Unauthenticated code execution via unrestricted avatar upload

Published Jun 20, 2023 · Updated Dec 9, 2024

Unrestricted file upload in FeehiCMS 2.0.8 allows remote attackers to execute arbitrary PHP through the profile avatar endpoint. The avatar workflow checked file suffixes only in client-side JavaScript, while the backend stored submitted PHP files and returned their upload paths. Unauthenticated network access is sufficient, and requesting a stored PHP payload executes it with the web server's privileges.

CVSS severity9.8
Critical
EPSS probability1.31%
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 FeehiCMS 2.0.8 allows remote attackers to execute arbitrary PHP through the profile avatar endpoint. The avatar workflow checked file suffixes only in client-side JavaScript, while the backend stored submitted PHP files and returned their upload paths. Unauthenticated network access is sufficient, and requesting a stored PHP payload executes it with the web server's privileges.

The record

CVE
CVE-2020-21489
Published
Jun 20, 2023
Updated
Dec 9, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1190, T1505.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 20, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 9, 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

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8GitHub Advisory DatabaseCVSS: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 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-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application
T1505.003Web Shell

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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