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Semantic Kernel has Arbitrary File Write via AI Agent Function Calling in .NET SDK

Critical severity GitHub Reviewed Published Feb 6, 2026 in microsoft/semantic-kernel • Updated Feb 20, 2026

Package

nuget Microsoft.SemanticKernel.Core (NuGet)

Affected versions

< 1.71.0

Patched versions

1.71.0
pip semantic-kernel (pip)
< 1.39.3
1.39.3

Description

Impact

What kind of vulnerability is it? Who is impacted?
An Arbitrary File Write vulnerability has been identified in Microsoft's Semantic Kernel .NET SDK, specifically within the SessionsPythonPlugin.
Developers who have built applications which include Microsoft's Semantic Kernel .NET SDK and are using the SessionsPythonPlugin

Patches

Has the problem been patched? What versions should users upgrade to?
The problem has been fixed in Microsoft.SemanticKernel.Plugins.Core version 1.71.0. Users should upgrade to version 1.71.0 or higher.

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?
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.

References

Are there any links users can visit to find out more?

References

@markwallace-microsoft markwallace-microsoft published to microsoft/semantic-kernel Feb 6, 2026
Published to the GitHub Advisory Database Feb 6, 2026
Reviewed Feb 6, 2026
Published by the National Vulnerability Database Feb 6, 2026
Last updated Feb 20, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(18th percentile)

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

CVE-2026-25592

GHSA ID

GHSA-2ww3-72rp-wpp4

Source code

Credits

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