CVE-2026-72817Public exploitNetwork attack vector

IP spoofing via unverified X-Forwarded-For precedence

Published Aug 14, 2026 · Updated Aug 14, 2026

IP spoofing in RealIP middleware in go-chi/chi 0.9.0 through 5.2.5 allows remote attackers to falsify request source addresses. The realIP function selects the first comma-separated X-Forwarded-For value and overwrites Request.RemoteAddr without establishing that a trusted proxy supplied the header. Exposure requires RealIP middleware and downstream reliance on RemoteAddr for access control, rate limiting, or logging, enabling control bypass or corrupted logs.

CVSS severity6.9
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

IP spoofing in RealIP middleware in go-chi/chi 0.9.0 through 5.2.5 allows remote attackers to falsify request source addresses. The realIP function selects the first comma-separated X-Forwarded-For value and overwrites Request.RemoteAddr without establishing that a trusted proxy supplied the header. Exposure requires RealIP middleware and downstream reliance on RemoteAddr for access control, rate limiting, or logging, enabling control bypass or corrupted logs.

The record

CVE
CVE-2026-72817
Published
Aug 14, 2026
Updated
Aug 14, 2026
Vendor
go-chi
Product
chi
Classifications
CWE-345, T1036
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 14, 2026CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=0.9.0 <5.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

go-chi · chiversion=0.9.0 <5.3.0

Published CVSS scores

6.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
6.9VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
6.9UbuntuCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity
T1036Masquerading

Public exploit references

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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