How severe is CVE-2021-39426?

CVE-2021-39426 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-39426 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-39426?

CVE-2021-39426 affects Seacms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-39426?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-39426 published?

CVE-2021-39426 was published on 2022-12-15 and last updated on 2026-06-17.

CVE-2021-39426

CVE-2021-39426 is a critical-severity vulnerability in Seacms with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-94.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-94
Affected product: Seacms
Published: 2022-12-15
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-39426?: CVE-2021-39426 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-39426 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39426?: CVE-2021-39426 affects Seacms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-39426?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-39426 published?: CVE-2021-39426 was published on 2022-12-15 and last updated on 2026-06-17.

References

https://github.com/seacms-com/seacms/issues/21

Affected products (1)

cpe:2.3:a:seacms:seacms:11.4:*:*:*:*:*:*:*

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