EUVD Vulnerability Catalog

EUVD-2026-112396

Severity: CRITICAL Base Score: 9.1 CVSS Version: 4.0

Vulnerability Description

Echo is a Go web framework. From 4.0.0 until 4.16.1 and 5.4.1, Echo's Proxy middleware selects a raw tunnel from a client WebSocket upgrade request before verifying that the configured upstream accepted the upgrade. If the upstream rejects the upgrade with an ordinary keep-alive response, later HTTP requests on the connection are sent directly to that upstream without passing through Echo's router or route-specific middleware. This can bypass authentication or authorization enforced only by Echo routes, but requires an accessible proxy route, a cooperating rejected-upgrade response, and a target without independent upstream authorization. This issue is fixed in 4.16.1 and 5.4.1.

CVSS Vector Analysis

Below is the complete, human-readable breakdown of the CVSS metric string: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

▪ Attack Vector (AV): Network
▪ Attack Complexity (AC): Low
▪ Attack Requirements (AT): Present
▪ Privileges Required (PR): None
▪ User Interaction (UI): None
▪ Vulnerability Confidentiality Impact (VC): High
▪ Vulnerability Integrity Impact (VI): High
▪ Vulnerability Availability Impact (VA): None
▪ Subsequent Confidentiality Impact (SC): None
▪ Subsequent Integrity Impact (SI): None
▪ Subsequent Availability Impact (SA): None

Affected Vendors & Systems

Vendor labstack

References & Advisory Links

Metadata Profile

Database Authority

European Union Agency for Cybersecurity (ENISA) EUVD

Assigner

GitHub_M

EPSS Probability

0

Known Aliases
CVE-2026-118264
Published On

2026-10-28

Last Updated

2026-10-28