CVE-2021-24217Public exploitNetwork attack vector

Remote code execution via unsafe event deserialization

Published Apr 12, 2021 · Updated Aug 3, 2024

PHP object injection in Facebook for WordPress before 3.0.0 allows remote attackers to execute code through crafted event data. The run_action function base64-decodes the event_data POST value and passes it to PHP unserialize(), allowing Guzzle's FileCookieJar destructor to write attacker-controlled PHP files. Exploitation is unauthenticated but requires a valid nonce generated from the site's nonce salt and key, so exposed WordPress secrets are a prerequisite for host-level code execution.

CVSS severity9.0
Critical
EPSS probability3.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

PHP object injection in Facebook for WordPress before 3.0.0 allows remote attackers to execute code through crafted event data. The run_action function base64-decodes the event_data POST value and passes it to PHP unserialize(), allowing Guzzle's FileCookieJar destructor to write attacker-controlled PHP files. Exploitation is unauthenticated but requires a valid nonce generated from the site's nonce salt and key, so exposed WordPress secrets are a prerequisite for host-level code execution.

The record

CVE
CVE-2021-24217
Published
Apr 12, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-502, CAPEC-586, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 12, 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?

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

8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
9.0WordfenceCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/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 exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
CAPEC-586Object Injection
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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