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Claude SDK for Python: Memory Tool Path Validation Race Condition Allows Sandbox EscapeGHSA-w828-4qhx-vxx3

MEDIUMFix: anthropics/anthropic-sdk-python@6599043

GHSA-w828-4qhx-vxx3 is a medium-severity (CVSS 5.3) CWE-59 vulnerability in anthropic. A fix is available for anthropic — see the affected versions and patch details below.

Also known asCVE-2026-34452PYSEC-2026-2115
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-w828-4qhx-vxx3.

EPSS Exploitation Probability

via FIRST.org ↗
0.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs4th percentile — riskier than 4% of all scored CVEsHighest risk
0.00%0.21%0.43%0.64%0.0%0.1%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍anthropic

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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!

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIanthropic≥ 0.86.0&&< 0.87.00.87.0pip install --upgrade 'anthropic==0.87.0'

Affected Products

1 product · 1 configurations
Application
claude sdk for pythonanthropic
≥ 0.86.0 && < 0.87.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for anthropic, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update anthropic to 0.87.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w828-4qhx-vxx3 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

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](https://hackerone.com/kasthel
O3 Security · Impact-Aware SCA

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Claude SDK for Python: Memory Tool Path Validation…