Summary
The BetaLocalFilesystemMemoryTool in the Anthropic TypeScript SDK created memory files and directories using the Node.js default modes (0o666 for files, 0o777 for directories), leaving them world-readable on systems with a standard umask and world-writable in environments with a permissive umask such as many Docker base images. A local attacker on a shared host could read persisted agent state, and in containerized deployments could modify memory files to influence subsequent model behavior.
Users on the affected versions are advised to update to the latest version.
Claude SDK thanks lucasfutures for the report.
Impact
A file, directory, or other resource is assigned permissions that allow broader access than intended. Typical impact: unauthorized read, modification, or execution of the resource.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-41686? CVE-2026-41686 is a medium-severity incorrect permission assignment for critical resource vulnerability in @anthropic-ai/sdk (npm), affecting versions >= 0.79.0, < 0.91.1. It is fixed in 0.91.1. A file, directory, or other resource is assigned permissions that allow broader access than intended.
- Which versions of @anthropic-ai/sdk are affected by CVE-2026-41686? @anthropic-ai/sdk (npm) versions >= 0.79.0, < 0.91.1 is affected.
- Is there a fix for CVE-2026-41686? Yes. CVE-2026-41686 is fixed in 0.91.1. Upgrade to this version or later.
- Is CVE-2026-41686 exploitable, and should I be worried? Whether CVE-2026-41686 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
- What actually determines whether CVE-2026-41686 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.
- How do I fix CVE-2026-41686? Upgrade
@anthropic-ai/sdkto 0.91.1 or later.