CVE-2026-40435: CWE-420: Unprotected Alternate Channel in F5 BIG-IP
When configured, IP-based access restrictions for httpd do not cover all endpoints, which may allow connections from blocked addresses. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-40435) affects F5 BIG-IP devices when IP-based access restrictions for the httpd service are configured. Due to incomplete coverage of all endpoints, some blocked IP addresses may still establish connections, constituting an unprotected alternate channel (CWE-420). The CVSS 3.1 base score is 5.3 (medium), reflecting network attack vector, low complexity, no privileges or user interaction required, and limited confidentiality impact. No official remediation or patch is currently documented, and no exploits are known in the wild.
Potential Impact
The vulnerability may allow unauthorized IP addresses to connect to certain httpd endpoints despite configured IP-based restrictions, potentially exposing limited information. There is no reported impact on data integrity or system availability. The overall impact is limited to partial bypass of access controls.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, review and tighten network access controls and monitor for unexpected connections. Avoid relying solely on IP-based restrictions for critical access control enforcement.
CVE-2026-40435: CWE-420: Unprotected Alternate Channel in F5 BIG-IP
Description
When configured, IP-based access restrictions for httpd do not cover all endpoints, which may allow connections from blocked addresses. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-40435) affects F5 BIG-IP devices when IP-based access restrictions for the httpd service are configured. Due to incomplete coverage of all endpoints, some blocked IP addresses may still establish connections, constituting an unprotected alternate channel (CWE-420). The CVSS 3.1 base score is 5.3 (medium), reflecting network attack vector, low complexity, no privileges or user interaction required, and limited confidentiality impact. No official remediation or patch is currently documented, and no exploits are known in the wild.
Potential Impact
The vulnerability may allow unauthorized IP addresses to connect to certain httpd endpoints despite configured IP-based restrictions, potentially exposing limited information. There is no reported impact on data integrity or system availability. The overall impact is limited to partial bypass of access controls.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, review and tighten network access controls and monitor for unexpected connections. Avoid relying solely on IP-based restrictions for critical access control enforcement.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- f5
- Date Reserved
- 2026-04-30T23:02:33.887Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a049708cbff5d8610dff47a
Added to database: 5/13/2026, 3:21:44 PM
Last enriched: 5/13/2026, 4:07:35 PM
Last updated: 5/14/2026, 6:49:09 AM
Views: 2
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