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CVE-2021-32777— Incorrect concatenation of multiple value request headers in ext-authz extension

Quick assessment

Affected
envoyproxy envoy
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.

Envoy是一款开源的分布式代理服务器。 Envoy 中存在安全漏洞。该漏洞允许攻击者绕过使用 ext_authz 扩展名的规则策略。 来自此漏洞的最大威胁是机密性、完整性以及系统可用性。

CVSS 8.6 · High EPSS 3.33% · P88

Possible ATT&CK Techniques 1 AI

T1550 · Use Alternate Authentication Material
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I. Basic Information for CVE-2021-32777

Vulnerability Information
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Vulnerability Title
Incorrect concatenation of multiple value request headers in ext-authz extension
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
不正确的行为次序：在解析与净化处理之前进行授权
Source: CVE Program / CVE List V5
Vulnerability Title
Envoy 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Envoy是一款开源的分布式代理服务器。 Envoy 中存在安全漏洞。该漏洞允许攻击者绕过使用 ext_authz 扩展名的规则策略。 来自此漏洞的最大威胁是机密性、完整性以及系统可用性。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
envoyproxy envoy >= 1.19.0, < 1.19.1 -

II. Public POCs for CVE-2021-32777

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III. Intelligence Information for CVE-2021-32777

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Vendor Advisories for CVE-2021-32777 (1)

Other References for CVE-2021-32777 (1)

Same Patch Batch · envoyproxy · 2021-08-24 · 5 CVEs total

CVE-2021-32779 8.6 HIGH Incorrectly handling of URI '#fragment' element as part of the path element
CVE-2021-32780 8.6 HIGH Incorrect handling of H/2 GOAWAY followed by SETTINGS frames
CVE-2021-32781 8.6 HIGH Continued processing of requests after locally generated response
CVE-2021-32778 5.8 MEDIUM Excessive CPU utilization when closing HTTP/2 streams

IV. Related Vulnerabilities

Same product: envoy
Same vendor: envoyproxy
Same weakness: CWE-551

V. Comments for CVE-2021-32777

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