CVE-2021-31920: Istio

Medium severity, CVSS 6.5. EPSS: 1.3% chance of exploitation in the next 30 days.

Istio before 1.8.6 and 1.9.x before 1.9.5 has a remotely exploitable vulnerability where an HTTP request path with multiple slashes or escaped slash characters (%2F or %5C) could potentially bypass an Istio authorization policy when path based authorization rules are used.

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 2021-05-27. Last modified 2026-06-17.