Executive brief
Anthropic's Sandbox Runtime is a security component used to isolate and execute untrusted code safely. A flaw in the network sandboxing logic fails to restrict network access when no allowed domains are configured, allowing sandboxed code to bypass network restrictions and make arbitrary external requests.
Technical details
The vulnerability is a logic error in the sandbox policy enforcement mechanism (CWE-693: Incomplete Data Sanitization). When a sandbox policy does not explicitly configure any allowed domains, the runtime incorrectly fails to enforce network isolation, permitting sandboxed code to initiate network requests that should have been blocked. This requires an attacker to have high privileges and present attack requirements to deploy or control the sandbox policy configuration. The impact is limited to confidentiality of the sandboxed environment. A patch was released in version 0.0.16.
Affected products
- Anthropic Sandbox Runtime before 0.0.16
Timeline
- 2025-12-04: disclosed
- 2025-12-04: patched: Fixed in v0.0.16