Vulnerability · Published Sep 14, 2026 · Assigned by VulnCheck

CVE-2026-91143goproxy through 15.3 Authentication Bypass via CONNECT

High 7.2

In plain English

A high-severity authentication bypass in goproxy from snail007. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities).

Severity (CVSS 3.1)7.2High

Exploit odds (30 days)0.5%top 59.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

goproxy through 15.3 fails to apply HTTP proxy basic authentication to CONNECT tunnel requests, allowing unauthenticated clients to bypass credential requirements. Attackers can issue CONNECT requests to establish tunnels through the authenticated proxy without providing credentials, enabling arbitrary TCP traffic relay and access to restricted destinations.

Affected products (as reported)

Vendor	Product	Versions
snail007	goproxy	0 – through 15.3

Weakness: CWE-288 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

References

Researcher write-up third-party-advisory, exploit
utils/structs.go at v15.3 technical-description
services/http.go at v15.3 technical-description
https://github.com/snail007/goproxy product
VulnCheck Advisory: goproxy through 15.3 Authentication Bypass via CONNECT third-party-advisory