Authentication Bypass Vulnerability in goproxy Product by Snail007
CVE-2026-91143

6.9MEDIUM

Key Information:

Vendor

Snail007

Status
Goproxy
Vendor
CVE Published:
14 September 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-91143?

The goproxy product prior to version 15.4 contains a flaw in its handling of HTTP proxy basic authentication. Specifically, it fails to enforce authentication for CONNECT tunnel requests, enabling unauthenticated clients to forge connections through the proxy. This vulnerability allows attackers to establish tunnels and relay arbitrary TCP traffic without valid credentials, potentially leading to unauthorized access to restricted resources. As such, it poses a significant risk to network security, highlighting the need for immediate remediation and security best practices.

Affected Version(s)

goproxy 0 <= 15.3

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-91143 - Proof of Concept

References

https://github.com/geo-chen/oss/blob/main/goproxy.md
third-party-advisoryexploit
https://github.com/snail007/goproxy/blob/v15.3/utils/stru...
technical-description
https://github.com/snail007/goproxy/blob/v15.3/services/h...
technical-description

CVSS V4

Score:
6.9
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

George Chen
.