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CVE-2026-118264— Echo: Rejected WebSocket upgrades can bypass Echo route-level access controls

Quick assessment

Affected
labstack echo
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Echo 是一个用 Go 编写的 Web 框架。在 4.0.0 至 4.16.1 以及 5.4.1 版本中，Echo 的 Proxy 中间件会在验证配置的上游是否接受 WebSocket 升级请求之前，就从客户端的 WebSocket 升级请求中选取原始隧道。如果上游以普通的保持连接（keep-alive）响应拒绝该升级，则此后在该连接上发出的 HTTP 请求将直接发送给该上游，而不会经过 Echo 的路由器或针对特定路由的中间件。此问题可绕过仅由 Echo 路由实施的认证或授权，但需要满足以下条件：存在可访问的代

CVSS 9.1 · Critical

Affected Version Matrix 2

VendorProduct Version RangeStatus
labstack echo >= 4.0.0, < 4.16.1 affected
>= 5.0.0, < 5.4.1 affected
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I. Basic Information for CVE-2026-118264

Vulnerability Information
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Vulnerability Title
Echo: Rejected WebSocket upgrades can bypass Echo route-level access controls
Source: CVE Program / CVE List V5
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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
HTTP请求的解释不一致性(HTTP请求私运)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
labstack echo >= 4.0.0, < 4.16.1 -

II. Public POCs for CVE-2026-118264

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III. Intelligence Information for CVE-2026-118264

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Other References for CVE-2026-118264 (5)

Same Patch Batch · labstack · 2026-10-28 · 16 CVEs total

CVE-2026-118260 8.2 HIGH Echo: BodyDump captures request and response bodies without size limits in v4
CVE-2026-118262 8.2 HIGH Echo: WebSocket proxy can retain connections and handlers after client disconnect
CVE-2026-118261 8.2 HIGH Echo: Decompress permits unbounded gzip expansion in v4
CVE-2026-118650 7.5 HIGH Echo: middleware.Static: `%2F`-encoded path bypasses route/group middleware guarding a sta
CVE-2026-118263 6.3 MEDIUM Echo: BodyDump can discard BodyLimit overflow errors for unknown-length requests
CVE-2026-118652 6.1 MEDIUM Echo: Reflected Cross-Site Scripting (XSS) via unsanitized JSONP callback in Context.JSONP
CVE-2026-118656 6.1 MEDIUM Echo: Open Redirect via Control-Character Prefix Defeating sanitizeURI
CVE-2026-118654 5.9 MEDIUM Echo static file middleware route protection bypass via encoded dot-dot traversal
CVE-2026-118655 5.9 MEDIUM Echo: Static Middleware Double-Unescape Path Traversal
CVE-2026-118657 5.9 MEDIUM Echo: HTTPS Redirect and HSTS Bypass via Unconditional Trust of Forwarded Scheme Headers
CVE-2026-118651 5.3 MEDIUM Echo: Reverse Proxy Forwards Attacker-Supplied X-Real-IP to Upstream by Default
CVE-2026-118266 5.3 MEDIUM Echo: CSRF Protection Bypass via MethodOverride Rewriting POST to Safe Method
CVE-2026-118265 5.3 MEDIUM Echo: X-Real-IP extractor trusts the header value instead of the sending peer
CVE-2026-118653 5.3 MEDIUM Echo: Rate Limiter Bypass via Spoofed X-Forwarded-For Header in Default Configuration
CVE-2026-118658 4.7 MEDIUM Echo: Arbitrary Scheme Injection in WWWRedirect/NonWWWRedirect Middlewares via X-Forwarded

IV. Related Vulnerabilities

Same product: echo
Same vendor: labstack
Same weakness: CWE-444