What is the CVSS score of CVE-2021-32777?

CVE-2021-32777 has a CVSS 3.1 base score of 8.3 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L. EPSS exploitation probability: 3.3%.

Envoy CVE-2021-32777

HIGH

Incorrect Behavior Order: Authorization Before Parsing and Canonicalization (CWE-551)

2021-08-24 security-advisories@github.com

Authentication Bypass Envoy

8.3

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

8.3 HIGH

AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

Low

Lifecycle Timeline

CVE Published

Aug 24, 2021 - 21:15 nvd

HIGH 8.3

DescriptionNVD

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.

AnalysisAI

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. Rated high severity (CVSS 8.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

Technical ContextAI

This vulnerability is classified under CWE-551. 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. Affected products include: Envoyproxy Envoy.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.