CVE-2021-39426Public exploitNetwork attack vector

Remote PHP code execution via notify configuration write

Published Dec 15, 2022 · Updated Apr 21, 2025

Code injection in SeaCMS 11.4 allows remote attackers to execute arbitrary PHP code through a crafted notify1 POST parameter. The action=set branch of /Upload/admin/admin_notify.php embeds notify1 directly into /data/admin/notify.php, letting quote-breaking input escape the generated string and become executable PHP. No authentication or user interaction is required, and the injected code runs in the web server's security context.

CVSS severity9.8
Critical
EPSS probability0.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in SeaCMS 11.4 allows remote attackers to execute arbitrary PHP code through a crafted notify1 POST parameter. The action=set branch of /Upload/admin/admin_notify.php embeds notify1 directly into /data/admin/notify.php, letting quote-breaking input escape the generated string and become executable PHP. No authentication or user interaction is required, and the injected code runs in the web server's security context.

The record

CVE
CVE-2021-39426
Published
Dec 15, 2022
Updated
Apr 21, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-94, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 15, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2025Record 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

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8CISA-ADPCVSS: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 exploitPublished

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code 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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