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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.

PUBLISHED Reserved 2026-03-27 | Published 2026-03-31 | Updated 2026-04-03 | Assigner GitHub_M




MEDIUM: 5.8CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

Problem types

CWE-59: Improper Link Resolution Before File Access ('Link Following')

CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

Product status

>= 0.86.0, < 0.87.0
affected

References

github.com/...python/security/advisories/GHSA-w828-4qhx-vxx3

github.com/...ommit/6599043eee6e86dce16953fcd1fd828052052be6

github.com/...pics/anthropic-sdk-python/releases/tag/v0.87.0

cve.org (CVE-2026-34452)

nvd.nist.gov (CVE-2026-34452)

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