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.
In Istio 1.5.0 though 1.5.8 and Istio 1.6.0 through 1.6.7, when users specify an AuthorizationPolicy resource with DENY actions using wildcard suffixes (e.g. *-some-suffix) for source principals or namespace fields, callers will never be denied access, bypassing the intended policy.
Istio 1.4.x before 1.4.9 and Istio 1.5.x before 1.5.4 contain the following vulnerability when telemetry v2 is enabled: by sending a specially crafted packet, an attacker could trigger a Null Pointer Exception resulting in a Denial of Service. This could be sent to the ingress gateway or a sidecar, triggering a null pointer exception which results in a denial of service. This also affects servicemesh-proxy where a null pointer exception flaw was found in servicemesh-proxy. When running Telemetry v2 (not on by default in version 1.4.x), an attacker could send a specially crafted packet to the ingress gateway or proxy sidecar, triggering a denial of service.