How severe is CVE-2021-4226?

CVE-2021-4226 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-2021-4226 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-4226?

CVE-2021-4226 affects Rsjoomla Rsfirewall!. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-4226?

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-2021-4226 published?

CVE-2021-4226 was published on 2022-12-15 and last updated on 2026-06-17.

CVE-2021-4226

CVE-2021-4226 is a critical-severity vulnerability in Rsjoomla Rsfirewall! 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-345.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (40th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-345
Affected product: Rsjoomla Rsfirewall!
Published: 2022-12-15
Last modified: 2026-06-17

Description

RSFirewall tries to identify the original IP address by looking at different HTTP headers. A bypass is possible due to the way it is implemented.

Frequently asked questions

What is CVE-2021-4226?: RSFirewall tries to identify the original IP address by looking at different HTTP headers. A bypass is possible due to the way it is implemented.
How severe is CVE-2021-4226?: CVE-2021-4226 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-2021-4226 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-4226?: CVE-2021-4226 affects Rsjoomla Rsfirewall!. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-4226?: 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-2021-4226 published?: CVE-2021-4226 was published on 2022-12-15 and last updated on 2026-06-17.

References

https://wpscan.com/vulnerability/c0ed80c8-ebbf-4ed9-b02f-31660097c352

Affected products (1)

cpe:2.3:a:rsjoomla:rsfirewall\!:*:*:*:*:*:wordpress:*:*

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