CVE-2021-24253Public exploitNetwork attack vector

Authenticated code execution via content-type-only upload validation

Published May 5, 2021 · Updated Aug 3, 2024

Unrestricted file upload in Classyfrieds 3.8 and earlier allows remote authenticated users to execute PHP code via Add Listing. The listing upload handler trusts the request-declared content type, accepts a PHP filename, and stores the file in a web-accessible user upload directory. Any authenticated WordPress account can reach the feature and execute the uploaded PHP file with the web server's privileges.

CVSS severity8.8
High
EPSS probability1.91%
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 Classyfrieds 3.8 and earlier allows remote authenticated users to execute PHP code via Add Listing. The listing upload handler trusts the request-declared content type, accepts a PHP filename, and stores the file in a web-accessible user upload directory. Any authenticated WordPress account can reach the feature and execute the uploaded PHP file with the web server's privileges.

The record

CVE
CVE-2021-24253
Published
May 5, 2021
Updated
Aug 3, 2024
Vendor
Classyfrieds Project
Product
Classyfrieds
Classifications
CWE-434, T1505.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 5, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=3.8 <=3.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Classyfrieds Project · Classyfriedsversion=3.8 <=3.8

Published CVSS scores

6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1505.003Server Software Component: Web 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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