What’s Vulnerable › Vulnerabilities

CVE-2026-114437: Chi Client IP Spoofing in ClientIPFromXFF via X-Forwarded-For

• Severity: medium (CVSS 4.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-21 · updated 2026-10-21
• Weakness: CWE-348

Description

In the Golang Chi web framework, the ClientIPFromXFF middleware skips any X-Forwarded-For entry in a configured trusted CIDR but never verifies that the direct TCP peer in http.Request.RemoteAddr belongs to that CIDR. A client that can reach the Go server directly can therefore append a trusted-looking proxy address and choose the client IP returned by middleware.GetClientIP. This issue affects chi before 5.4.0.

Affected products

• go-chi chi: before 5.4.0 — fixed in 5.4.0

How to fix

Upgrade to a fixed version: go-chi chi 5.4.0. Check the vendor advisory for mitigations.

References

• https://github.com/go-chi/chi/security/advisories/GHSA-j6qf-3m9c-vwj3
• https://www.tenable.com/security/research/tra-2026-66

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