CVE-2026-25592 Security Alert: CRITICAL Vulnerability

Urgent: CVE-2026-25592 requires immediate attention.

· 4 min read

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Executive Summary

A critical Arbitrary File Write vulnerability (CVE-2026-25592) has been discovered in Microsoft's Semantic Kernel .NET SDK, specifically affecting the SessionsPythonPlugin. This vulnerability poses a significant risk to developers using this SDK in their applications, allowing unauthorized file writes that could compromise system integrity. Immediate action is required to mitigate potential exploitation.

Immediate Action

  • Upgrade to Microsoft.SemanticKernel.Core version 1.70.0 or higher immediately.
  • Review your application for any use of the SessionsPythonPlugin and assess the risk.
  • Implement a Function Invocation Filter to validate file paths if upgrading is not immediately possible.
  • Monitor for any updates from Microsoft regarding this vulnerability and related security advisories.
  • Consider isolating affected services until the patch is applied.

Affected Versions

  • Microsoft.SemanticKernel.Core@<=1.69.9 vulnerable; upgrade to 1.70.0+
  • pip semantic-kernel@<=1.x.x vulnerable; upgrade to 1.x.x+

Resolution Guide

To upgrade to the patched version, use the following commands based on your development environment:

dotnet add package Microsoft.SemanticKernel.Core --version 1.70.0
pip install semantic-kernel --upgrade

If you need to implement a workaround, add the following code snippet to create a Function Invocation Filter:

public class MyFunctionInvocationFilter : IFunctionInvocationFilter
{
    public async Task InvokeAsync(FunctionInvocationContext context, FunctionInvocationDelegate next)
    {
        // Validate localFilePath
        if (!IsValidPath(context.Arguments["localFilePath"]))
        {
            throw new InvalidOperationException("Invalid file path");
        }
        await next(context);
    }

    private bool IsValidPath(string path)
    {
        // Implement your allow-list logic here
        return true; // Placeholder
    }
}

Detection & Verification

To check if your version is vulnerable, run the following commands:

dotnet list package --include-transitive
pip list

Verify the fix by checking the installed version:

dotnet list package
pip show semantic-kernel

Risk and Impact

The vulnerability allows attackers to write arbitrary files on the server where the application is running, which could lead to unauthorized access, data corruption, or even full system compromise. The blast radius includes any application that utilizes the vulnerable versions of the Semantic Kernel SDK, potentially affecting user data and application integrity.

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