CVE-2026-47221: envoy from 1.18.0 (inclusive), before 1.35.13 (exclusive), from 1.36.0 (inclusive), before 1.36.9 (exclusive), from…

Affected technology

envoy · from 1.18.0 (inclusive), before 1.35.13 (exclusive)
envoyproxy

envoy · from 1.36.0 (inclusive), before 1.36.9 (exclusive)
envoyproxy

envoy · from 1.37.0 (inclusive), before 1.37.5 (exclusive)
envoyproxy

envoy · from 1.38.0 (inclusive), before 1.38.3 (exclusive)
envoyproxy

envoy · >= 1.38.0, < 1.38.3, >= 1.37.0, < 1.37.5, >= 1.36.0, < 1.36.9, >= 1.18.0, < 1.35.13
envoyproxy

Component: Not specified by the source

Attack conditions (Vendor/CNA, CVSS 3.1): Network (remote) · No privileges required · No user interaction required

Attack conditions (NVD, CVSS 3.1): Network (remote) · No privileges required · No user interaction required

What an attacker can do

The source says when route configured with internal_redirect_policy including 303 in redirect_response_codes and upstream must return HTTP 303 response, an unauthenticated attacker can exploit this to cause complete denial of service, terminating all active connections. Vendor/CNA’s CVSS 3.1 assessment (base score 5.9/10) rates confidentiality and integrity impact as none; availability impact as high. NVD’s CVSS 3.1 assessment (base score 7.5/10) rates confidentiality and integrity impact as none; availability impact as high.