CVE-2026-118264 Echo - Authentication Bypass

Echo 4.0.0 to 4.16.1 and 5.x before 5.4.1 contain an authentication bypass caused by Proxy middleware forwarding requests after upstream rejects WebSocket upgrade, letting attackers bypass Echo route authentication, exploit requires accessible proxy route and cooperating upstream.

CVSS base score 9.1 /10
Critical
CISA KEV
Not listed
Public exploit
None known
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Broken Authentication
CVSS vector
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
28 October 2026
Updated
29 October 2026
Weakness
CWE-444

Vendor fix

Update to versions 4.16.1 or 5.4.1 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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