Answer in brief
CVE-2026-118264 records a Critical severity (CVSS 9.1) vulnerability in Echo: Rejected WebSocket upgrades can bypass Echo route-level access controls. The current sources do not mark it as known exploited. The current feed maps labstack/echo (generic), github.com/labstack/echo/v4 (go), github.com/labstack/echo/v4 (go), github.com/labstack/echo/v5 (go) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps labstack/echo (generic), github.com/labstack/echo/v4 (go), github.com/labstack/echo/v4 (go), github.com/labstack/echo/v5 (go) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| labstack/echogeneric | >=4.0.0 <4.16.1 || >=5.0.0 <5.4.1 | 4.16.1, 5.4.1 |
| github.com/labstack/echo/v4go | >=4.0.0,<4.16.1 | 4.16.1 |
| github.com/labstack/echo/v4go | >=4.0.0 <4.16.1 | 4.16.1 |
| github.com/labstack/echo/v5go | >=5.0.0,<5.4.1 | 5.4.1 |
| github.com/labstack/echo/v5go | >=5.0.0 <5.4.1 | 5.4.1 |
Published upstream
Oct 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 23, 2026
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.
Quoted source text, attributed separately from HOL analysis.