Input validation error in envoy - CVE-2026-47220
Published: June 24, 2026
Vulnerability identifier: #VU135114
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-47220
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Cloud Native Computing Foundation
Affected software:
envoy
envoy
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper input validation in the %REQUESTED_SERVER_NAME(X:Y)% log format handler when processing requests with a missing host-related header while host fallback options are configured. A remote attacker can send a specially crafted request to cause a denial of service.
Exploitation requires the log format to use %REQUESTED_SERVER_NAME(X:Y)% with host-related fallback options such as HOST_FIRST, SNI_FIRST, or ORIG.
How to mitigate CVE-2026-47220
Install security update from vendor's website.