CVE-2026-22686: enclave-vm Vulnerable to Sandbox Escape via Host Error Prototype Chain

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.8%, percentile 55: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 55% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes enclave-vm (npm) < 2.7.0, fixed in 2.7.0. Check your lockfile, including transitive dependencies.

What it is

Enclave is a secure JavaScript sandbox designed for safe AI agent code execution. Prior to 2.7.0, there is a critical sandbox escape vulnerability in enclave-vm that allows untrusted, sandboxed JavaScript code 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. An attacker can intentionally trigger a host error, then climb the prototype chain. Using the host Function constructor, arbitrary JavaScript can be compiled and executed in the host context, fully bypassing the sandbox and granting access to sensitive resources such as process.env, filesystem, and network. This breaks enclave-vm’s core security guarantee of isolating untrusted code. This vulnerability is fixed in 2.7.0.

From the GitHub advisory

A critical sandbox escape vulnerability exists in enclave-vm (affected:

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.

Weakness type: CWE-693, CWE-94.

Product: enclave-vm (npm) · Assigned by: GitHub_M · Published: 2026-01-13

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.75% probability of exploitation activity in the next 30 days; percentile 55.

Timeline

• 2026-01-13 — CVE record published by GitHub_M
• 2026-01-14 — CVE record last updated
• 2026-01-14 — GitHub-reviewed advisory GHSA-7qm7-455j-5p63 published (critical)

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-7qm7-455j-5p63 github.com
2. CVE.org record CVE-2026-22686 cve.org
3. NVD entry CVE-2026-22686 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com

Critical npm advisories · Today’s Security Digest