CVE-2026-34452: anthropic claude_sdk_for_python Link Following

Vulnerability summary

CVE-2026-34452 is a medium (CVSS 5.8) Link Following vulnerability in anthropic claude_sdk_for_python. EPSS estimates a 0.14% chance of exploitation in the next 30 days, higher than 2.6% of scored vulnerabilities.

Timeline

1. 31-03-2026
   PublishedVulnerability first disclosed.
2. 03-04-2026
   Last modifiedVulnerability information updated.

Description

The Claude SDK for Python provides access to the Claude API from Python applications. From version 0.86.0 to before version 0.87.0, the async local filesystem memory tool in the Anthropic Python SDK validated that model-supplied paths resolved inside the sandboxed memory directory, but then returned the unresolved path for subsequent file operations. A local attacker able to write to the memory directory could retarget a symlink between validation and use, causing reads or writes to escape the sandbox. The synchronous memory tool implementation was not affected. This issue has been patched in version 0.87.0.

• CWE-59Improper Link Resolution Before File Access ('Link Following')The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
• CWE-367Time-of-check Time-of-use (TOCTOU) Race ConditionThe product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.