CVE-2025-66479

Network sandbox escape via empty domain allowlist

Published Dec 4, 2025 · Updated Dec 5, 2025

Protection mechanism failure in Anthropic Sandbox Runtime before 0.0.16 allows local users to make unrestricted outbound requests. SandboxManager tied needsNetworkRestriction to whether allowedDomains contained entries, so an empty list skipped the macOS or Linux network-isolation path instead of blocking all traffic. Code must already execute inside a sandbox configured with an empty allowedDomains list; exploitation permits outbound connections that can disclose data accessible to the sandboxed process.

CVSS severity1.8
Low
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Protection mechanism failure in Anthropic Sandbox Runtime before 0.0.16 allows local users to make unrestricted outbound requests. SandboxManager tied needsNetworkRestriction to whether allowedDomains contained entries, so an empty list skipped the macOS or Linux network-isolation path instead of blocking all traffic. Code must already execute inside a sandbox configured with an empty allowedDomains list; exploitation permits outbound connections that can disclose data accessible to the sandboxed process.

The record

CVE
CVE-2025-66479
Published
Dec 4, 2025
Updated
Dec 5, 2025
Vendor
Anthropic
Product
Anthropic Sandbox Runtime
Classifications
CWE-693
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.0.16

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Anthropic · Anthropic Sandbox Runtimeversion=< 0.0.16

Published CVSS scores

1.8GitHubCVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-693Protection Mechanism Failure

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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