Cyber Resilience

CVE-2026-26030

RCE in Microsoft Semantic Kernel ≤ 1.39.4

Published
19 February 2026
Modified
03 March 2026
Patch / advisory
CVSS Score v3.1 9.9
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.037 89th percentile
Risk Priority 74 floored blend · peak EPSS

Summary

CVE-2026-26030 is a critical-severity Code Injection (CWE-94) vulnerability in Microsoft Semantic Kernel. Its CVSS base score is 9.9 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 11% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

This vulnerability is AI-related — categorised as AI Agent Protocols and Integrations; in the Supply Chain and Deployment risk domain.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-26030 is a remote code execution vulnerability (CWE-94: Code Injection) affecting Microsoft's Semantic Kernel Python SDK in versions prior to 1.39.4. The flaw resides specifically in the `InMemoryVectorStore` filter functionality, allowing arbitrary code execution. The vulnerability was published on 2026-02-19 and carries a CVSS v3.1 base score of 9.9, reflecting its critical severity.

An attacker with low privileges (PR:L) can exploit this over the network (AV:N) with low complexity (AC:L) and no user interaction (UI:N). Successful exploitation leads to high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H), with a changed scope (S:C), enabling full system compromise on affected deployments.

Mitigation is available via upgrade to version python-1.39.4 or higher, as detailed in the GitHub security advisory (GHSA-xjw9-4gw8-4rqx), release notes, and associated pull request. As a workaround, avoid using `InMemoryVectorStore` in production scenarios.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Semantic Kernel, Microsoft's semantic kernel Python SDK, has a remote code execution vulnerability in versions prior to 1.39.4, specifically within the `InMemoryVectorStore` filter functionality. The problem has been fixed in version `python-1.39.4`. Users should upgrade this version or higher. As…

more

a workaround, avoid using `InMemoryVectorStore` for production scenarios.

CWE(s)

AI Security AnalysisAI

AI Category
AI Agent Protocols and Integrations
Risk Domain
Supply Chain and Deployment
OWASP Top 10 for LLMs 2025
None mapped
Classification Reason
Matched keywords: semantic kernel

Related Threats

MITRE ATT&CK Enterprise Techniques

T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
T1059.002 AppleScript Execution
Adversaries may abuse AppleScript for execution.
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
T1059.005 Visual Basic Execution
Adversaries may abuse Visual Basic (VB) for execution.
T1059.006 Python Execution
Adversaries may abuse Python commands and scripts for execution.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2013-3906Same vendor: Microsoft
CVE-2024-21643Same vendor: Microsoft
CVE-2009-0556Same vendor: Microsoft
CVE-2024-43469Same vendor: Microsoft
CVE-2023-36572Same vendor: Microsoft
CVE-2024-29991Same vendor: Microsoft
CVE-2026-21537Same vendor: Microsoft
CVE-2023-33157Same vendor: Microsoft
CVE-2023-35333Same vendor: Microsoft
CVE-2023-36573Same vendor: Microsoft

Affected Assets

microsoft
semantic kernel
≤ 1.39.4

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V1.3.1

Mitigating Controls (NIST 800-53 r5) AI

Developer testing and evaluation finds code paths that accept and execute externally influenced strings.

Input validation directly stops untrusted data from being used to construct executable code without neutralization.

Least privilege limits the damage an injected code fragment can perform once executed.

Requiring documented secure development standards and tools enforces use of safe code-generation APIs and escaping.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

PR.PS-06's SDLC practices directly target injection flaws via secure coding and testing (mostly), yet as a single broad outcome it leaves many code-generation specifics unaddressed (partial).

PR.DS-10 none match
prevents

PR.DS-10 protects runtime data confidentiality/integrity but has no bearing on neutralizing externally influenced input during code generation, so neither direction shows any preventive effect.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

prevents

Banning unapproved code samples and unauthenticated web services, combined with secure-coding standards and SAST, prevents the dynamic generation or inclusion of attacker-supplied code.

none

Controls that restrict unauthorized or malicious code from being introduced via external networks or removable media limit opportunities for an attacker to inject and execute arbitrary code.

References