CVE-2021-31921
CVSS v3
9.8
CRITICAL
EPSS Score
1.5 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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.
Technical details
- Published
- 2021-06-02
Frequently asked questions
What is CVE-2021-31921?
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.
Is CVE-2021-31921 actively exploited?
Active exploitation of CVE-2021-31921 has not been confirmed. Its EPSS score was 1.5% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-31921?
CVE-2021-31921 has a CVSS v3 base score of 9.8 (CRITICAL severity).
Is CVE-2021-31921 affecting your environment?
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