How severe is CVE-2021-4451?

CVE-2021-4451 has a CVSS 3.x base score of 6.6, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-4451 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-4451?

CVE-2021-4451 affects Nintechnet Ninjafirewall. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-4451?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2021-4451 have an EU (EUVD) identifier?

Yes. CVE-2021-4451 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34636.

When was CVE-2021-4451 published?

CVE-2021-4451 was published on 2024-10-16 and last updated on 2026-06-17.

CVE-2021-4451

CVE-2021-4451 is a medium-severity vulnerability in Nintechnet Ninjafirewall with a CVSS 3.x base score of 6.6. 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-502.

Key facts

Severity: Medium (CVSS 3.x base score 6.6)
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2021-34636
Weakness: CWE-502
Affected product: Nintechnet Ninjafirewall
Published: 2024-10-16
Last modified: 2026-06-17

Description

The NinjaFirewall plugin for WordPress is vulnerable to Authenticated PHAR Deserialization in versions up to, and including, 4.3.3. This allows authenticated attackers to perform phar deserialization on the server. This deserialization can allow other plugin or theme exploits if vulnerable software is present (WordPress, and NinjaFirewall).

Frequently asked questions

What is CVE-2021-4451?: The NinjaFirewall plugin for WordPress is vulnerable to Authenticated PHAR Deserialization in versions up to, and including, 4.3.3. This allows authenticated attackers to perform phar deserialization on the server. This deserialization can allow other plugin or theme exploits if vulnerable software is present (WordPress, and NinjaFirewall).
How severe is CVE-2021-4451?: CVE-2021-4451 has a CVSS 3.x base score of 6.6, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-4451 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-4451?: CVE-2021-4451 affects Nintechnet Ninjafirewall. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-4451?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2021-4451 have an EU (EUVD) identifier?: Yes. CVE-2021-4451 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-34636.
When was CVE-2021-4451 published?: CVE-2021-4451 was published on 2024-10-16 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nintechnet:ninjafirewall:*:*:*:*:*:wordpress:*:*

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