CVE-2021-32777: envoyproxy envoy

Vulnerability summary

CVE-2021-32777 is a high (CVSS 8.6) vulnerability in envoyproxy envoy. EPSS estimates a 3.33% chance of exploitation in the next 30 days, higher than 88.4% of scored vulnerabilities.

Timeline

1. 24-08-2021
   PublishedVulnerability first disclosed.
2. 03-08-2024
   Last modifiedVulnerability information updated.

Description

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions when ext-authz extension is sending request headers to the external authorization service it must merge multiple value headers according to the HTTP spec. However, only the last header value is sent. This may allow specifically crafted requests to bypass authorization. Attackers may be able to escalate privileges when using ext-authz extension or back end service that uses multiple value headers for authorization. A specifically constructed request may be delivered by an untrusted downstream peer in the presence of ext-authz extension. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to the ext-authz extension to correctly merge multiple request header values, when sending request for authorization.

• CWE-551Incorrect Behavior Order: Authorization Before Parsing and CanonicalizationIf a web server does not fully parse requested URLs before it examines them for authorization, it may be possible for an attacker to bypass authorization protection.
• CWE-863Incorrect AuthorizationThe product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.