CVE-2026-72817
Description
A flaw was found in the go-chi/chi component. The RealIP middleware, responsible for resolving the request source IP, does not properly validate trusted proxies when processing the X-Forwarded-For header. A remote attacker can exploit this by prepending a forged IP address to the X-Forwarded-For header, leading to IP spoofing. This could allow the attacker to bypass access controls or falsify request logs.
Statement
A flaw in the go-chi/chi RealIP middleware allows remote attackers to spoof source IP addresses (Request.RemoteAddr). The middleware parses the first IP address in the X-Forwarded-For header without verifying if the immediate HTTP proxy peer is trusted. An unauthenticated attacker can prepend an arbitrary IP address to the X-Forwarded-For header, causing applications relying on RealIP for request context to misidentify the client source. This enables bypassing application-level IP-based access control lists (ACLs) or spoofing identity in audit logs.
Mitigation
Disable the default `RealIP` middleware and replace it with a proxy-aware middleware (such as `httputil.ReverseProxy` or custom header parsing) that strictly validates upstream reverse proxies against an explicit list of trusted CIDR ranges before accepting `X-Forwarded-For` headers.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 6.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | Low |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Frequently Asked Questions
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