Istio Reference

Scope

Look-up facts for Istio: supported releases and support windows, Kubernetes / Envoy / Gateway API version mapping, feature maturity, 2026 security bulletins, ports, installation profiles and Helm charts, labels and annotations, security API values, certificate defaults, and resource and performance figures. Values were checked against the release-1.31 branch of istio/istio.io (the branch that builds istio.io) and the release-1.3x branches of istio/istio on 2026-09-25. For why things work this way see Explanation; for tasks see How-to Guides.

Release and Support Matrix

Istio ships a minor release roughly once a quarter. Each minor release is supported until 6 weeks after the N+2 minor release ships; patch releases inherit the support window of their minor. The control plane may be at most one minor version ahead of the data plane (never behind); Istio recommends revisions so that there is no skew at all.

Minor	Release date	Latest patch (date)	End of life	Kubernetes support	Envoy branch	Gateway API dependency
1.31	2026-08-31 (announcement; support table says Aug 27)	1.31.1 (2026-09-21)	~Feb 2027 (expected)	1.32 - 1.36	release/v1.39	v1.6.0
1.30	2026-05-18 (announcement; support table says May 14)	1.30.5 (2026-09-21)	~Dec 2026 (expected)	1.32 - 1.36	release/v1.38	v1.5.1
1.29	2026-02-16	1.29.8 (2026-09-21)	2026-10-12 (expected)	1.31 - 1.35	release/v1.37	v1.4.1
1.28 (EOL)	2025-11-05	1.28.10 (2026-07-01)	2026-07-01	1.30 - 1.34	release/v1.36	TBD (not checked)
1.27 (EOL)	2025-08-11	TBD (not checked)	2026-04-07	1.29 - 1.33	TBD	TBD
1.26 (EOL)	2025-05-08	-	2025-12-22	1.29 - 1.33	-	-
1.25 (EOL)	2025-03-03	-	2025-09-30	1.29 - 1.32	-	-
1.24 (EOL)	2024-11-07	-	2025-06-24	1.28 - 1.31	-	-

Date discrepancies in upstream data

The istio.io support-status table (data/compatibility/supportStatus.yml) lists 1.31 as released "Aug 27, 2026" and 1.30 as "May 14, 2026", while the release announcements carry publishdate 2026-08-31 and 2026-05-18. This page uses the announcement dates. The supported-releases page's "Patched versions with no known CVEs" table (1.31.0+, 1.30.0+, 1.29.2+) is also stale: ISTIO-SECURITY-2026-004/-006 affect 1.30.0-1.30.3 and 1.29.0-1.29.6. Run the latest patch of a supported minor.

Artifact hosting changed in 1.31: Istio no longer publishes to gcr.io/istio-release, registry.istio.io or istio-release.storage.googleapis.com. Images stay on Docker Hub, Helm charts move to https://blob.istio.io/istio-release/charts, OCI charts to ghcr.io/istio/release/charts. "Scream tests" that disable the GCP-hosted artifacts run on 2026-09-15, 2026-10-13, 2026-11-17 and 2026-12-08/09 (UTC).

Sources: Supported Releases, Announcing Istio 1.31.0, Announcing Istio 1.31.1, Gateway API versions from each branch's go.mod in istio/istio.

Feature Maturity Timeline

Feature	Status	Since	Notes
istiod (merged Pilot, Citadel, Galley)	Stable	1.5 (2020)	Single control plane binary
Ambient mode (ztunnel, waypoints, APIs)	Stable / GA	1.24 (2024-11-07)	Beta in 1.22 (2024-05-13)
Delta (incremental) xDS on by default	Default	1.22	State-of-the-world xDS still supported
DNS proxying on by default for ambient	Default	1.25
DNS capture + iptables reconciliation default for ambient	Default	1.29
Native sidecars (ENABLE_NATIVE_SIDECARS=true)	Default	1.27	Per-pod opt-out: sidecar.istio.io/nativeSidecar: "false"
Native nftables backend	Available	1.27 (sidecar), 1.28 (ambient)	--set values.global.nativeNftables=true
Dual-stack IPv4/IPv6	Beta	1.28
Ambient multicluster	Alpha 1.27; multi-network multi-primary Beta 1.29	1.27	Single-network and primary-remote topologies unsupported (see limitations below)
Gateway API Inference Extension (InferencePool)	Beta	1.29	Enable with ENABLE_GATEWAY_API_INFERENCE_EXTENSION
CRL support for plugged-in CAs	Available	1.27 (sidecar), 1.29 (ztunnel)
agentgateway as Gateway API gateway	Experimental	1.30	GatewayClass istio-agentgateway, PILOT_ENABLE_AGENTGATEWAY=true
agentgateway as waypoint	Experimental	1.31	GatewayClass istio-agentgateway-waypoint
TrafficExtension API (Wasm + Lua)	New	1.30	Replaces WasmPlugin as the primary extension API
Helm v4 (server-side apply)	Supported	1.30
Weighted waypoint canaries	New	1.31	istio.io/use-waypoint-canary label + weight annotation
Zone-aware load balancing (zoneAwareLbSetting)	New	1.31
ALLOW_ANY_DYNAMIC_DNS outbound policy	New	1.31	Envoy Dynamic Forward Proxy for unknown hosts
FIPS 140-3 compliance policy	New	1.31	COMPLIANCE_POLICY=fips-140-3
EnvoyFilter on waypoints	Not supported	-	Stated in the 1.26 announcement; use TrafficExtension/Wasm

Ambient multicluster limitations (as of 1.31 docs)

Only multi-network, multi-primary deployments are supported; single-network multicluster is untested; primary-remote does not work; waypoints must be deployed with identical names in every cluster; service scope must be uniform across clusters. The "Sidecar or ambient?" page still lists multicluster, multi-network, VM support and sidecar-to-waypoint interoperability as not implemented in ambient; the multicluster install page is newer and authoritative for multicluster.

Sources: release announcements for 1.22, 1.24, 1.27, 1.28, 1.29, 1.30, 1.31; Ambient multicluster install.

Security Bulletins (2026)

Bulletin	Date	Max CVSS	Affected	Fixed in	Istio-specific issues
ISTIO-SECURITY-2026-001	2026-03-10	8.7	1.29.0, 1.28.0-1.28.4, 1.27.0-1.27.7	1.29.1, 1.28.5, 1.27.8 (derived from affected ranges)	CVE-2026-31837 JWKS resolver failure may allow auth bypass using known default keys (8.7); CVE-2026-31838 debug endpoints allow cross-namespace proxy data access (6.9); plus Envoy CVEs
ISTIO-SECURITY-2026-002	2026-03-21	5.9	All releases with the mesh gateway option on VirtualService	No fix (by design)	VirtualService with mesh gateway can redirect other tenants' traffic in namespace-based multi-tenancy. Mitigation: move to Gateway API or apply the hardening in the linked blog
ISTIO-SECURITY-2026-003	2026-04-20	5.4	1.29.0-1.29.1, 1.28.0-1.28.5	1.29.2, 1.28.6	CVE-2026-39350 AuthorizationPolicy serviceAccounts regex injection via unescaped dots; CVE-2026-41413 SSRF via RequestAuthentication jwksUri
ISTIO-SECURITY-2026-004	2026-06-04	7.5	1.30.0, 1.29.0-1.29.3, 1.28.0-1.28.7	1.30.1, 1.29.4, 1.28.8	Envoy CVE-2026-47774 (HTTP/2 memory exhaustion via cookie header HPACK amplification)
ISTIO-SECURITY-2026-005	2026-06-24	7.5	1.30.1-1.30.2, 1.29.4-1.29.5, 1.28.8-1.28.9	1.30.3, 1.29.6, 1.28.10 (derived)	14 Envoy CVEs (HTTP/3, ext_authz, ext_proc, OAuth2, SAN NUL-byte validation)
ISTIO-SECURITY-2026-006	2026-08-27	7.7	1.30.0-1.30.3, 1.29.0-1.29.6 (and 1.31.0 for the BackendTLSPolicy issue)	1.30.4, 1.29.7, 1.31.1	EnvoyFilter proxyVersion regex control-plane DoS (now capped at 1024 chars); GHSA-qm8v-g4f9-qhjx BackendTLSPolicy fails open to plaintext on sidecars when CA ref is unresolved (6.8); Envoy RBAC safe_regex fail-open and path-parameter bypass CVEs

Sources: Istio security bulletins, e.g. ISTIO-SECURITY-2026-006, namespace-based multi-tenancy blog.

Ports

Sidecar proxy (Envoy + pilot-agent):

Port	Protocol	Purpose	Pod-internal only
15000	TCP	Envoy admin	Yes
15001	TCP	Envoy outbound capture	No
15002	TCP	Failure detection	Yes
15004	HTTP	Debug	Yes
15006	TCP	Envoy inbound capture	No
15008	HTTP/2	HBONE mTLS tunnel	No
15020	HTTP	Merged Prometheus telemetry (agent + Envoy + app)	No
15021	HTTP	Health checks	No
15053	DNS	DNS proxy (when capture is enabled)	Yes
15090	HTTP	Envoy Prometheus telemetry	No

Control plane (istiod):

Port	Protocol	Purpose
443	HTTPS	Webhook service port
15010	gRPC	xDS and CA, plaintext (secure networks only; debug endpoints need auth since 1.30)
15012	gRPC	xDS and CA over TLS/mTLS (production)
15014	HTTP	Control plane monitoring (debug endpoint authorization on by default since 1.29)
15017	HTTPS	Webhook container port (forwarded from 443)

ztunnel (ambient):

Port	Purpose	Bound in pod network namespace
15001	Pod outbound capture	Yes
15006	Pod inbound plaintext capture	Yes
15008	Pod inbound HBONE capture	Yes
15080	Pod outbound SOCKS5	Yes
15021	Readiness	No
15000	Admin (localhost only)	No
15020	Metrics	No

Note

Network policies must allow TCP 15008 in and out of every ambient pod.

Sources: Application requirements - ports used by Istio, ztunnel ARCHITECTURE.md.

Installation Profiles and Helm Charts

Profile	istioctl installs	Use
default	istiod + ingress gateway	Production, primary clusters
demo	istiod + ingress + egress gateways; high tracing and access-log levels	Bookinfo and tasks; not for performance tests
minimal	istiod only	Control plane; gateways installed separately
remote	Remote-cluster config	Cluster managed by an external or primary-cluster control plane
empty	Nothing	Base for custom configuration
preview	Experimental features	Testing
ambient	istiod + istio-cni + ztunnel (ingress gateway disabled)	Ambient mode; ingress via Gateway API, waypoints deployed per namespace/service afterwards

Platform profiles (global.platform=gke|eks|openshift|...) are applied on top of a deployment profile. With Helm, pass the same profile to every chart.

Helm chart	Release name (docs)	Mode
istio/base	istio-base	Both (CRDs, cluster roles)
istio/istiod	istiod	Both
istio/cni	istio-cni	Required for ambient, optional for sidecar
istio/ztunnel	ztunnel	Ambient
istio/gateway	e.g. istio-ingress	Both

Sources: Configuration profiles, Install ambient with Helm.

Labels and Annotations

Key	On	Effect
istio-injection=enabled	Namespace	Sidecar injection by the default revision
istio.io/rev=<revision or tag>	Namespace / pod	Sidecar injection by a specific revision or revision tag
sidecar.istio.io/inject: "false"	Pod	Opt a pod out of injection
sidecar.istio.io/nativeSidecar	Pod	Force native sidecar on/off (overrides ENABLE_NATIVE_SIDECARS)
istio.io/dataplane-mode=ambient	Namespace / pod	Enrol in ambient (no restart needed)
istio.io/dataplane-mode=none	Pod	Exclude a pod from ambient
istio.io/use-waypoint=<name>	Namespace / service / pod	Send east-west traffic for the target through that waypoint
istio.io/use-waypoint-namespace	Namespace / service / pod	Waypoint lives in another namespace
istio.io/ingress-use-waypoint=true	Service / namespace	Ingress gateway traffic also goes through the waypoint (1.25+)
istio.io/waypoint-for	Waypoint Gateway	service (default), workload, all, none
istio.io/use-waypoint-canary, istio.io/use-waypoint-canary-namespace, istio.io/use-waypoint-canary-weight (annotation)	Service / namespace	Weighted waypoint canary (1.31)
ambient.istio.io/xfcc-include-client-identity: "true"	Waypoint Gateway	Waypoint synthesizes XFCC from the source SPIFFE ID (1.30)

GatewayClasses used in the docs: istio (ingress/egress gateways), istio-waypoint (waypoints), plus the experimental istio-agentgateway (1.30) and istio-agentgateway-waypoint (1.31). Multicluster east-west gateways are generated with samples/multicluster/gen-eastwest-gateway.sh.

Sources: Use a waypoint, Resource labels, Resource annotations.

xDS Resources

xDS API	Purpose	Consumers
LDS (Listener)	Inbound/outbound listeners	Sidecars, gateways, waypoints
RDS (Route)	HTTP routes (VirtualService, HTTPRoute)	Sidecars, gateways, waypoints
CDS (Cluster)	Upstream clusters (services, subsets)	Sidecars, gateways, waypoints
EDS (Endpoint)	Endpoint addresses (EndpointSlices, WorkloadEntry)	Sidecars, gateways, waypoints
SDS (Secret)	Certificates and keys, served by pilot-agent	Sidecars, gateways, waypoints
WDS (Workload/Address) and Authorization	Istio-specific simplified resources for workloads, services and L4 policy	ztunnel

Delta (incremental) xDS is the default since 1.22. On reconnect, ztunnel reports the name and version of every WDS resource; in 1.31 this can exceed istiod's 4 MiB gRPC receive limit at about 40,000 workloads (raise ISTIO_GPRC_MAXRECVMSGSIZE, about 1 MiB per 10,000 workloads and services).

Security API Values

PeerAuthentication mtls.mode:

Mode	Behavior
STRICT	Only mTLS accepted; plaintext rejected
PERMISSIVE	mTLS and plaintext both accepted (migration)
DISABLE	mTLS disabled
UNSET	Inherit from parent (namespace, then mesh); mesh default is PERMISSIVE

AuthorizationPolicy action:

Action	Behavior
CUSTOM	Delegate the decision to an external authorizer (extensionProviders); evaluated first
DENY	Deny matching requests; evaluated after CUSTOM
ALLOW	Allow matching requests; if any ALLOW policy selects a workload, non-matching requests are denied
AUDIT	Mark matching requests for audit logging; does not affect allow/deny

Evaluation order: CUSTOM -> DENY -> ALLOW. Principals use the form cluster.local/ns/<namespace>/sa/<service-account> (the SPIFFE ID without spiffe://). requestPrincipals use <iss>/<sub>; ["*"] means "any valid JWT". Since 1.31 (backported to 1.30.2), source.trustDomains / notTrustDomains match the peer certificate's trust domain.

Sources: Security concepts - authorization, PeerAuthentication reference.

Certificate Defaults

Item	Default	Notes
Workload identity	spiffe://<trust-domain>/ns/<ns>/sa/<sa>	Trust domain default cluster.local
Workload certificate lifetime	24 hours	Rotated by pilot-agent (sidecar) or ztunnel before expiry
Self-signed root CA	Generated by istiod at install (istio-ca-secret)	Validity commonly cited as 10 years (unverified in current docs)
Plugged-in CA	cacerts secret in istio-system (ca-cert.pem, ca-key.pem, root-cert.pem, cert-chain.pem)	Intermediate per cluster; used for multicluster trust
External signers	Kubernetes CSR API / cert-manager istio-csr	istiod acts as RA
CRL	Supported for plugged-in CAs	ztunnel CRL since 1.29

Resource and Performance Figures

Official figures (Istio 1.24 load tests: 1000 services, 2000 pods, 70,000 mesh-wide RPS; per-proxy figures at 1000 RPS with 1 KB payloads):

Component	CPU	Memory
Sidecar proxy (2 worker threads)	~0.20 vCPU	~60 MB
Waypoint proxy (2 worker threads)	~0.25 vCPU	~60 MB
ztunnel	~0.06 vCPU	~12 MB

Latency charts for no-mesh vs ambient L4 vs ambient L4+L7 vs sidecar were measured on 5 bare-metal Equinix M3 Large machines with Flannel, http/1.1, 1 KB payload, 500-1500 RPS, 4 client connections, 2 proxy workers, mTLS on. The docs publish charts only; read values from the performance page.

Vault estimates carried over from earlier notes (not controlled benchmarks; hardware, versions and methodology unrecorded - use only as rough guidance):

Metric	Sidecar (Envoy)	Ambient (ztunnel, L4)	No mesh
Added latency P50	+1-2 ms	+0.5 ms	Baseline
Added latency P99	+3-10 ms	+1-3 ms	Baseline
Throughput	90-95% of native	95-98% of native	100%
Memory per pod	+50-100 Mi	0 (shared per node)	0
CPU per pod	+50-100m	0 (shared per node)	0

Pods in mesh	istiod CPU	istiod memory	Config push time
100	200m	512 Mi	< 1 s
1,000	1-2 cores	2-4 Gi	1-5 s
5,000	4-8 cores	8-16 Gi	5-15 s
10,000	8-16 cores	16-32 Gi	15-30 s

Dimension	Rough practical limit (estimate)	Driver
Pods per mesh	10,000+ per istiod deployment (scale istiod horizontally)	Push fan-out
Services	5,000+	xDS size; use Sidecar / discovery selectors
VirtualServices	5,000+	Envoy route table size
Ambient workloads	~40,000 before the 4 MiB WDS reconnect limit (1.31)	Raise ISTIO_GPRC_MAXRECVMSGSIZE

Starting resource requests (vault estimates; tune from metrics):

Component	CPU request	Memory request	Notes
istiod	500m	2 Gi	Scales with config and proxy count
Sidecar (Envoy)	100m	128 Mi	Per pod
Ingress gateway	1000m	1 Gi	Scales with traffic
ztunnel	50m	64 Mi	Per node; official measurement ~12 MB at 1000 RPS

Sources: Performance and scalability, 1.31 upgrade notes.