EUVD-2026-17681
GHSA-w828-4qhx-vxx3
CVSS Vector
CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
4Description
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.
Analysis
Symlink race condition in Anthropic Python SDK async filesystem memory tool (versions 0.86.0-0.86.x) allows local authenticated attackers to escape sandbox restrictions and read or write arbitrary files outside the designated memory directory. The vulnerability exploits a time-of-check-time-of-use (TOCTOU) flaw where path validation occurs before symlink resolution, enabling an attacker with memory directory write access to redirect file operations via symlink manipulation. …
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