# CVE-2026-72817: go-chi chi 0.9.0 before 5.3.0 IP Spoofing via X-Forwarded-For

CVE-2026-72817 is fixed in 6 products on 1 platform, first by DEBIAN-CVE-2026-72817, released August 14, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-72817
- Priority: Routine
- CVSS: 6.5 (Moderate)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 14, 2026
- Weakness: Insufficient Verification of Data Authenticity
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72817

## Description

go-chi/chi versions 0.9.0 before 5.3.0 contains an IP spoofing vulnerability in the RealIP middleware, which resolves the request source IP (Request.RemoteAddr) using the first IP in the X-Forwarded-For header without validating trusted proxies. A malicious client can prepend a forged IP as the first value of the X-Forwarded-For header to spoof the request source IP, potentially bypassing access controls or falsifying request logs.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | cloudflared opensuse-leap 16.0 | 2026.8.2-bp160.1.1 | [OPENSUSE-SU-2026:21670-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21670-1.md) | Aug 27, 2026 |
| Linux | golang-github-go-chi-chi Debian 14 | 5.3.0-1 | [DEBIAN-CVE-2026-72817](https://patchblox.com/security/data/fix/linux/debian-cve-2026-72817.md) | Aug 14, 2026 |
| Linux | hauler opensuse-leap 16.0 | 2.1.0-bp160.1.1 | [OPENSUSE-SU-2026:21793-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21793-1.md) | Sep 3, 2026 |
| Linux | trivy opensuse-leap 16.0 | 0.74.0-160000.1.1 | [OPENSUSE-SU-2026:21645-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21645-1.md) | Aug 25, 2026 |
| Linux | v2ray-core opensuse-leap 16.0 | 5.53.0-bp160.1.1 | [OPENSUSE-SU-2026:21653-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21653-1.md) | Aug 25, 2026 |
| Linux | warewulf4 opensuse-leap 16.0 | 4.7.1-bp160.1.1 | [OPENSUSE-SU-2026:21918-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21918-1.md) | Sep 18, 2026 |

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Data as of 2026-11-10T01:44:33Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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