CVE-2026-26030
📋 TL;DR
Microsoft Semantic Kernel Python SDK versions before 1.39.4 contain a remote code execution vulnerability in the InMemoryVectorStore filter functionality. Attackers can execute arbitrary code on affected systems by exploiting improper input validation. This affects all users running vulnerable versions of the Semantic Kernel Python SDK.
💻 Affected Systems
- Microsoft Semantic Kernel Python SDK
📦 What is this software?
Semantic Kernel by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands, steal data, install malware, or pivot to other systems.
Likely Case
Remote code execution leading to data exfiltration, service disruption, or unauthorized access to system resources.
If Mitigated
Limited impact with proper network segmentation and least privilege controls, potentially only affecting the application container.
🎯 Exploit Status
Based on CVSS 9.9 score and CWE-94 (Improper Control of Generation of Code), exploitation appears straightforward once details are known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: python-1.39.4
Vendor Advisory: https://github.com/microsoft/semantic-kernel/security/advisories/GHSA-xjw9-4gw8-4rqx
Restart Required: Yes
Instructions:
1. Update Semantic Kernel Python SDK: pip install semantic-kernel==1.39.4
2. Restart all services using the SDK
3. Verify no older versions remain in your environment
🔧 Temporary Workarounds
Avoid InMemoryVectorStore in production
allDo not use InMemoryVectorStore for production scenarios as recommended by Microsoft
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected systems
- Apply application-level input validation and sanitization for InMemoryVectorStore filter parameters
🔍 How to Verify
Check if Vulnerable:
Check Semantic Kernel version: python -c "import semantic_kernel; print(semantic_kernel.__version__)" and verify it's below 1.39.4Check Version:
python -c "import semantic_kernel; print(f'Semantic Kernel version: {semantic_kernel.__version__}')"Verify Fix Applied:
Confirm version is 1.39.4 or higher using the same command and test InMemoryVectorStore functionality📡 Detection & Monitoring
Log Indicators:
- Unusual process execution from Semantic Kernel processes
- Unexpected system commands in application logs
- Errors or crashes in InMemoryVectorStore operations
Network Indicators:
- Unexpected outbound connections from Semantic Kernel services
- Command and control traffic patterns
SIEM Query:
process.name:python AND process.args:*semantic_kernel* AND (process.args:*sh* OR process.args:*cmd* OR process.args:*powershell*)