Cyber Resilience

CVE-2021-4226

CriticalPublic PoC

Published: 15 December 2022

Published
15 December 2022
Modified
27 May 2025
KEV Added
Patch
CVSS Score v3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0015 34.7th percentile
Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-4226 is a critical-severity Insufficient Verification of Data Authenticity (CWE-345) vulnerability in Rsjoomla Rsfirewall\!. Its CVSS base score is 9.8 (Critical).

Operationally, ranked at the 34.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

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.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

rsjoomla
rsfirewall\!
≤ 1.1.25

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-345

Directly requires independent verification of matching output before adverse decisions, mitigating insufficient authenticity checks on data from external sources.

addresses: CWE-345

Use of approved PKI certificates provides verifiable data authenticity and origin for communications and artifacts.

addresses: CWE-345

Mandates provision of authenticity and integrity artifacts that enable verification of name/address resolution data.

addresses: CWE-345

Requires explicit verification of data authenticity from authoritative sources, preventing acceptance of unauthenticated resolution responses.

addresses: CWE-345

Control requires verification of data authenticity/integrity (e.g., checksums) after aggregation/packing, directly reducing exploitation of insufficient verification before transmission.

addresses: CWE-345

Time synchronization supports reliable freshness verification when checking data authenticity across systems or components.

addresses: CWE-345

Mandates verification of data authenticity for software, firmware, and information.

addresses: CWE-345

Provenance documentation and monitoring directly enables verification of authenticity for components and data throughout their history.

References