Unauthenticated IP-block bypass via trusted proxy headers
Published Dec 15, 2022 · Updated Apr 21, 2025
IP-block bypass in RSJoomla! RSFirewall! before 1.1.25 allows remote attackers to evade blocklists via spoofed proxy headers. The client-IP routine accepts a configured HTTP proxy header such as X-Real-IP without establishing that a trusted proxy supplied it, so a request can claim an unblocked address. Exposure requires selection of an attacker-controlled proxy header instead of REMOTE_ADDR; bypassed requests retain normal site access.
Summary
What happened
IP-block bypass in RSJoomla! RSFirewall! before 1.1.25 allows remote attackers to evade blocklists via spoofed proxy headers. The client-IP routine accepts a configured HTTP proxy header such as X-Real-IP without establishing that a trusted proxy supplied it, so a request can claim an unblocked address. Exposure requires selection of an attacker-controlled proxy header instead of REMOTE_ADDR; bypassed requests retain normal site access.
The record
- CVE
- CVE-2021-4226
- Published
- Dec 15, 2022
- Updated
- Apr 21, 2025
- Vendor
- RSJoomla!
- Product
- RSFirewall!
- Classifications
- CWE-345, CWE-639
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 15, 2022CVE publishedPublication date reported by the CVE source.
- Apr 21, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.1.25
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- WPScan proxy-header IP-block bypass proof of conceptproof of concept · validated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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