CVE-2026-118264
Description
A flaw was found in Echo's Proxy middleware. When a client requests a WebSocket upgrade, the middleware establishes a direct network tunnel before verifying whether the upstream server accepted the upgrade. If the upstream server rejects the upgrade while keeping the connection alive, subsequent HTTP requests sent over that connection bypass Echo's routing and route-specific middleware. A remote attacker can exploit this flaw to gain unauthorized access to protected upstream resources that rely solely on Echo for access control.
Statement
A flaw was found in the Echo Go web framework's Proxy middleware. When processing a client WebSocket upgrade request, the middleware establishes a raw tunnel before verifying that the upstream server accepted the upgrade. If the upstream rejects the upgrade with a standard keep-alive response, subsequent HTTP requests over the existing connection bypass Echo's router and route-specific middleware, allowing unauthenticated or unauthorized access to upstream resources that rely solely on Echo for access control.
Mitigation
Disable or avoid using the Proxy middleware for WebSocket upgrade paths until a patched version is deployed, or enforce independent authentication and authorization directly at the upstream service layer.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.4 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | High | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Understanding the Weakness (CWE)
Integrity,Non-Repudiation,Access Control
Technical Impact: Unexpected State; Hide Activities; Bypass Protection Mechanism
An attacker could create HTTP messages to exploit a number of weaknesses including 1) the message can trick the web server to associate a URL with another URL's webpage and caching the contents of the webpage (web cache poisoning attack), 2) the message can be structured to bypass the firewall protection mechanisms and gain unauthorized access to a web application, and 3) the message can invoke a script or a page that returns client credentials (similar to a Cross Site Scripting attack).
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