Unauthenticated access-control bypass via untrusted proxy headers
Published Aug 14, 2026 · Updated Aug 14, 2026
IP spoofing in go-chi chi 5.2.1 through 5.2.5 allows remote attackers to bypass IP-based controls through RealIP middleware. The realIP function takes the leftmost X-Forwarded-For value supplied by a client and assigns it to RemoteAddr without validating the proxy chain. Exploitation requires an application to enable RealIP and trust that address for access control, rate limiting, or logging, enabling restricted access, limit evasion, or forged attribution.
Summary
What happened
IP spoofing in go-chi chi 5.2.1 through 5.2.5 allows remote attackers to bypass IP-based controls through RealIP middleware. The realIP function takes the leftmost X-Forwarded-For value supplied by a client and assigns it to RemoteAddr without validating the proxy chain. Exploitation requires an application to enable RealIP and trust that address for access control, rate limiting, or logging, enabling restricted access, limit evasion, or forged attribution.
The record
- CVE
- CVE-2026-72815
- Published
- Aug 14, 2026
- Updated
- Aug 14, 2026
- Vendor
- go-chi
- Product
- chi
- Classifications
- CWE-940, CWE-345, CWE-290, T1036
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 14, 2026CVE publishedPublication date reported by the CVE source.
- Aug 14, 2026Record 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=5.2.1 <5.3.0
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
- RealIP IP-restriction bypass proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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