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CVE-2026-34452

Claude SDK for Python: Memory Tool Path Validation Race Condition Allows Sandbox Escape

5.8 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
Low
Availability
None

Exploit likelihood

0.14%Up 0.1 points since Apr 1, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.8

Claude SDK for Python: Memory Tool Path Validation Race Condition Allows Sandbox Escape

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.

Record
CVE-2026-34452
CVSS 4.0
5.8 MediumCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-59, CWE-367
Updated
2026-11-02
EUVDEUVD-2026-17681 5.8

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.

Record
EUVD-2026-17681
CVSS 4.0
5.8 MediumCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-w828-4qhx-vxx3 5.8

Claude SDK for Python: Memory Tool Path Validation Race Condition Allows Sandbox Escape

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.

Users on the affected versions are advised to update to the latest version.

Claude SDK for Python thanks hackerone.com/kasthelord for reporting this issue!

Record
GHSA-w828-4qhx-vxx3
CVSS 4.0
5.8 MediumCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
5.3 MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-59, CWE-367
Updated
2026-11-02
NVD 5.8

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.

Record
CVE-2026-34452
CVSS 4.0
5.8 MediumCVSS: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
CVSS 3.1
5.3 MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-59, CWE-367
Updated
2026-11-02
OSV 5.8

Claude SDK for Python: Memory Tool Path Validation Race Condition Allows Sandbox Escape

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.

Record
CVE-2026-34452
CVSS 4.0
5.8 MediumCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-367, CWE-59
Updated
2026-11-02
OSVGHSA-w828-4qhx-vxx3 5.8

Claude SDK for Python: Memory Tool Path Validation Race Condition Allows Sandbox Escape

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.

Users on the affected versions are advised to update to the latest version.

Claude SDK for Python thanks hackerone.com/kasthelord for reporting this issue!

Record
GHSA-w828-4qhx-vxx3
CVSS 4.0
5.8 MediumCVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
5.3 MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-367, CWE-59
Updated
2026-11-02
OSVPYSEC-2026-2115 5.3

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.

Record
PYSEC-2026-2115
CVSS 3.1
5.3 MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
anthropic
PyPI
 0.86.0 up to 0.87.0
0.87.0

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-34452 is a medium vulnerability (CVSS 5.8) in Anthropic Claude Sdk For Python, published March 31, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.14%, the 3rd percentile. Fixed in anthropic 0.87.0.

References

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