What is CVE-2021-39426?

CVE-2021-39426 is a critical-severity vulnerability in Seacms, classified under Code Injection. CVSS score: 9.8/10. Published 2022-12-15.

How severe is CVE-2021-39426?

Critical severity. CVSS v3 base score is 9.8 out of 10.

RCE in Seacms

CVE-2021-39426

An issue was discovered in /Upload/admin/admin_notify.php in Seacms 11.4 allows attackers to execute arbitrary php code via the notify1 parameter when the action parameter equals set.

Vulnerability class: RCE (Remote Code Execution)

Published 2022-12-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (57.6th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: +0.000

Affected products

Seacms — versions 11.4

Weakness classification (CWE)

CWE-94 — Code Injection

References

github.com/seacms-com/seacms/issues/21 (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2021-39426?: CVE-2021-39426 is a critical-severity vulnerability in Seacms, classified under Code Injection. CVSS score: 9.8/10. Published 2022-12-15.
How severe is CVE-2021-39426?: Critical severity. CVSS v3 base score is 9.8 out of 10.