CVE-2021-4226 json
RSFirewall < 1.1.25 - IP Block Bypass
published 2022-12-15 3 y ago modified 2026-06-17 4 mo ago also EUVD-2021-34084
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 46%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- Unknown RSFirewall! 1.1.25
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- total
- Assessed
- 18 mo ago
Exploit prediction
0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- wpscan.com https://wpscan.com/vulnerability/c0ed80c8-ebbf-4ed9-b02f-31660097c352 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
Affected products
- Unknown RSFirewall!
Classification
- Weakness
-
- CWE-345 Insufficient Verification of Data Authenticity
- Technology feeds
References
-
wpscan.com
/vulnerability/c0ed80c8-ebbf-4ed9-b02f-31660097c352
exploit, vdb-entry, technical-description, third-party-advisory
Sources
- CVE List CVE-2021-4226
- NVD CVE-2021-4226
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.