CVE-2021-31921: Istio

Critical severity, CVSS 9.8. EPSS: 1.5% chance of exploitation in the next 30 days.

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.

Affected products

• Istio Istio: before 1.8.6 (fixed in 1.8.6); from 1.9.0, before 1.9.5 (fixed in 1.9.5)

Published 2021-06-02. Last modified 2026-06-17.