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Vulnerability record · CVE-2021-31921 · published 2 June 2021

CVE-2021-31921: Istio missing authorization vulnerability

Istio · Istio

Istio before 1.8.6 and 1.9.x before 1.9.5 contains a remotely exploitable vulnerability where an external client can access unexpected services in the cluster, bypassing authorization checks, when a gateway is configured with AUTO_PASSTHROUGH routing configuration.

9.8 CVSS 3.1 Critical EPSS 1.5% · top 27.6% CWE-862 · Missing authorization
9.8CVSS 3.1 base score, v2 6.8
1.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

Istio before 1.8.6 and 1.9.x before 1.9.5 contains a remotely exploitable vulnerability where an external client can access unexpected services in the cluster, bypassing authorization checks, when a gateway is configured with AUTO_PASSTHROUGH routing configuration.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://istio.io/latest/news/security/istio-security-2021-006/ ExploitVendor Advisory
https://istio.io/latest/news/security/istio-security-2021-006/ ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-31921), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.