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securitycritical PriorityID: envoy-gateway-wasm-oci-sandbox-verification-guardrail

Envoy Gateway Wasm OCI Dynamic Module Sandbox & Cryptographic Verification

Enforces strict memory isolation, resource ceilings, and cryptographic supply-chain verification for dynamic WebAssembly (Wasm) filters loaded from OCI registries into Envoy Gateway data planes. Prevents noisy-neighbor OOM host crashes and remote code execution by requiring Cosign/Notary v2 digest pinning and explicit V8/Wasmtime linear memory constraints before filter initialization.

Prohibited Anti-Pattern: Loading Unsigned Wasm Modules with Uncapped Virtual Memory Across Envoy Filter Chains

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---
description: Envoy Gateway Wasm OCI Dynamic Module Sandbox & Cryptographic Verification - Enforces strict memory isolation, resource ceilings, and cryptographic supply-chain verification for dynamic WebAssembly (Wasm) filters loaded from OCI registries into Envoy Gateway data planes. Prevents noisy-neighbor OOM host crashes and remote code execution by requiring Cosign/Notary v2 digest pinning and explicit V8/Wasmtime linear memory constraints before filter initialization.
globs: **/*wasm*.{yaml,yml,json,ts}, **/envoy-gateway/**/*.{yaml,yml,json}, **/k8s/**/*.{yaml,yml}, **/filters/**/*.{ts,rs,go,yaml}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/envoy-gateway-wasm-oci-sandbox-verification-guardrail"
---

# Envoy Gateway Wasm OCI Dynamic Module Sandbox & Cryptographic Verification

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: Loading Unsigned Wasm Modules with Uncapped Virtual Memory Across Envoy Filter Chains

## System Constraints
You are a Principal Security Architect enforcing Envoy Gateway Wasm OCI Sandbox Verification Guardrails. Mandate that every dynamic WebAssembly filter loaded from an OCI registry is immutably pinned by cryptographic sha256 digest, verified via verifiable supply-chain policies (Cosign/Sigstore), and sandboxed with deterministic max linear memory limits (vmConfig) and fail-closed fault policies. Prevent worker thread exhaustion, unauthenticated bytecode execution, and proxy panics by enforcing zero-trust Wasm injection standards across all gateway and ingress manifests.

## Strict Guidelines
- Engineers MUST ALWAYS reference dynamic Wasm modules via immutable sha256 digest digests (image:tag@sha256:...) rather than mutable semantic version tags.
- Engineers MUST configure explicit max_memory allocations inside vmConfig to restrict Wasm linear heap expansion and prevent Envoy host worker OOM crashes.
- Services MUST implement fail-closed behavior (fail_open: false) for security-critical edge filters such as token introspectors, rate limiters, or WAF modules.
- Engineers MUST NOT configure Wasm OCI pull mechanisms that bypass cryptographic verification via Sigstore Cosign keyless signatures or pinned public verification keys.
- Wasm runtime configurations SHOULD strictly employ 'envoy.wasm.runtime.v8' or 'envoy.wasm.runtime.wasmtime' with deterministic resource ceiling boundaries defined in EnvoyExtensionPolicy or Envoy Gateway custom resources.

## Bad vs Good Implementations
### EnvoyExtensionPolicy Wasm OCI Configuration

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Using a mutable image tag exposes the proxy to supply-chain poisoning. Setting failOpen: true bypasses security checks if the filter panics, and omitting linear memory constraints enables malicious or buggy bytecode to cause Envoy host worker OOM termination.
```yaml
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: EnvoyExtensionPolicy
metadata:
  name: insecure-wasm-filter
  namespace: ingress-gateway
spec:
  targetRef:
    group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: edge-api-route
  wasm:
    - name: dynamic-auth-filter
      rootID: "edge_auth"
      code:
        type: Image
        image: registry.example.internal/filters/auth-edge:latest # Flaw: Mutable tag prone to MITM / drift
      failOpen: true # Flaw: Fails open on crash or corrupt bytecode, bypassing auth
      # Flaw: Missing vmConfig resource constraints, allowing unconstrained linear memory expansion
```

#### Production Standard (Correct)
> **Standard**: Pins the Wasm OCI artifact with an immutable SHA-256 cryptographic digest, enforces a strict fail-closed (failOpen: false) isolation posture, and bounds the V8 engine's linear memory footprint to 32MB to prevent host memory starvation.
```yaml
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: EnvoyExtensionPolicy
metadata:
  name: secure-wasm-filter
  namespace: ingress-gateway
spec:
  targetRef:
    group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: edge-api-route
  wasm:
    - name: dynamic-auth-filter
      rootID: "edge_auth"
      code:
        type: Image
        # Invariant: Immutable SHA256 image digest verified by cluster Cosign policy
        image: registry.example.internal/filters/auth-edge@sha256:a1b2c3d4e5f67890abcdef1234567890abcdef1234567890abcdef1234567890
        pullSecretRef:
          name: regcred-read-only
      failOpen: false # Invariant: Fail-closed ensures traffic is blocked if filter panics
      vmConfig:
        runtime: "envoy.wasm.runtime.v8"
        configuration:
          maxLinearMemoryMB: 32 # Invariant: Hard ceiling prevents host noisy-neighbor OOM
          allowPrecompiled: true
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

Kubernetes Resource Evaluator
Inspects and validates EnvoyExtensionPolicy and Gateway API CRDs against structural security schemas and resource constraints.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

Cosign Image Attestation Verifier
Verifies cryptographic signatures, attestation provenance, and SBOM manifests of OCI-packaged WebAssembly modules prior to proxy deployment.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Envoy Gateway Wasm OCI Dynamic Module Sandbox & Cryptographic Verification

Envoy Gateway Wasm OCI Dynamic Module Sandbox & Cryptographic Verification defines an industrial-grade behavioral standard for security engineering. Enforces strict memory isolation, resource ceilings, and cryptographic supply-chain verification for dynamic WebAssembly (Wasm) filters loaded from OCI registries into Envoy Gateway data planes. Prevents noisy-neighbor OOM host crashes and remote code execution by requiring Cosign/Notary v2 digest pinning and explicit V8/Wasmtime linear memory constraints before filter initialization. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Loading Unsigned Wasm Modules with Uncapped Virtual Memory Across Envoy Filter Chains Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftLoading Unsigned Wasm Modules with Uncapped Virtual Memory Across Envoy Filter ChainsCritical
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Engineers MUST ALWAYS reference dynamic Wasm modules via immutable sha256 digest digests (image

Engineers MUST ALWAYS reference dynamic Wasm modules via immutable sha256 digest digests (image:tag@sha256:...) rather than mutable semantic version tags.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

Engineers MUST configure explicit max_memory allocations inside vmConfig to restrict Wasm linear heap expansion and prevent Envoy host worker OOM crashes.

Engineers MUST configure explicit max_memory allocations inside vmConfig to restrict Wasm linear heap expansion and prevent Envoy host worker OOM crashes.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

Services MUST implement fail-closed behavior (fail_open

Services MUST implement fail-closed behavior (fail_open: false) for security-critical edge filters such as token introspectors, rate limiters, or WAF modules.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
4

Engineers MUST NOT configure Wasm OCI pull mechanisms that bypass cryptographic verification via Sigstore Cosign keyless signatures or pinned public verification keys.

Engineers MUST NOT configure Wasm OCI pull mechanisms that bypass cryptographic verification via Sigstore Cosign keyless signatures or pinned public verification keys.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
5

Wasm runtime configurations SHOULD strictly employ 'envoy.wasm.runtime.v8' or 'envoy.wasm.runtime.wasmtime' with deterministic resource ceiling boundaries defined in EnvoyExtensionPolicy or Envoy Gateway custom resources.

Wasm runtime configurations SHOULD strictly employ 'envoy.wasm.runtime.v8' or 'envoy.wasm.runtime.wasmtime' with deterministic resource ceiling boundaries defined in EnvoyExtensionPolicy or Envoy Gateway custom resources.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Envoy Gateway Wasm OCI Dynamic Module Sandbox & Cryptographic Verification critical for AI coding assistants?

Enforces strict memory isolation, resource ceilings, and cryptographic supply-chain verification for dynamic WebAssembly (Wasm) filters loaded from OCI registries into Envoy Gateway data planes. Prevents noisy-neighbor OOM host crashes and remote code execution by requiring Cosign/Notary v2 digest pinning and explicit V8/Wasmtime linear memory constraints before filter initialization. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Loading Unsigned Wasm Modules with Uncapped Virtual Memory Across Envoy Filter Chains) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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