CVE-2026-34451: Claude SDK for TypeScript: Memory Tool Path Validation Allows Sandbox Escape to Sibling Directories
Claude SDK for TypeScript provides access to the Claude API from server-side TypeScript or JavaScript applications. From version 0.79.0 to before version 0.81.0, the local filesystem memory tool in the Anthropic TypeScript SDK validated model-supplied paths using a string prefix check that did not append a trailing path separator. A model steered by prompt injection could supply a crafted path that resolved to a sibling directory sharing the memory root's name as a prefix, allowing reads and writes outside the sandboxed memory directory. This issue has been patched in version 0.81.0.
Other sources
The local filesystem memory tool in the Anthropic TypeScript SDK validated model-supplied paths using a string prefix check that did not append a trailing path separator. A model steered by prompt injection could supply a crafted path that resolved to a sibling directory sharing the memory root's name as a prefix, allowing reads and writes outside the sandboxed memory directory.
Users on the affected versions are advised to update to the latest version.
Claude SDK for TypeScript thanks hackerone.com/nicksim for reporting this issue!
— GitHub
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/@anthropic-ai/sdkto a version that resolves this vulnerability.Fixed in 0.81.0 - Upgrade
Upgrade
Claude SDK for TypeScriptto a version that resolves this vulnerability.Fixed in 0.81.0
Event History
Frequently Asked Questions
What is the severity of CVE-2026-34451?
CVE-2026-34451 is classified as a critical vulnerability due to its potential for sandbox escape affecting local file systems.
How do I fix CVE-2026-34451?
To fix CVE-2026-34451, update the Claude SDK for TypeScript to version 0.81.0 or later.
What versions of Claude SDK for TypeScript are affected by CVE-2026-34451?
CVE-2026-34451 affects Claude SDK for TypeScript versions from 0.79.0 to before 0.81.0.
What types of applications are impacted by CVE-2026-34451?
CVE-2026-34451 impacts server-side TypeScript or JavaScript applications using the Claude SDK.
What does CVE-2026-34451 allow an attacker to do?
CVE-2026-34451 allows attackers to potentially escape the sandbox and access sibling directories, compromising security.