CVE-2026-26030: Microsoft Semantic Kernel InMemoryVectorStore filter remote code execution vulnerability
CVE-2026-26030 is a critical remote code execution flaw in the InMemoryVectorStore filter functionality of the Microsoft Semantic Kernel Python SDK, classified as CWE-94 (Code Injection). The record states that versions before 1.39.4 are affected and that the issue is fixed in 1.39.4. The available sources recommend upgrading and, as an interim measure, avoiding InMemoryVectorStore in production.
Overview
CVE-2026-26030 affects the Microsoft Semantic Kernel Python SDK. According to the record, the flaw is in the filter functionality of the InMemoryVectorStore component and can lead to remote code execution. The record classifies it as CWE-94 (Code Injection) and marks it as critical.
Impact
The CVSS metrics in the record describe network attack vector, low attack complexity, low privileges required, no user interaction and scope change, with high impact on confidentiality, integrity and availability. Scores of 9.9 and 10 (both CVSS 3.1 from GitHub sources) appear in the record. No NVD-assigned score is present in the record.
Affected products and versions
- Microsoft Semantic Kernel (Python SDK): versions before 1.39.4.
- The record lists the affected range as lower than 1.39.4. The lower bound of the affected range is not stated.
Exploitation status
The record shows the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. No confirmed exploitation appears in the sources consulted. The record's SSVC data lists exploitation as none and automatable as no. The EPSS probability is 0.04134 with a percentile of 0.90794.
Remediation and mitigation
- Upgrade Microsoft Semantic Kernel Python packages to 1.39.4 or a later release, as recommended by the vendor advisory.
- As a workaround listed in the advisory, avoid using InMemoryVectorStore in production scenarios until the upgrade is applied.
- Review the release notes and the linked pull request to confirm the scope of the fix.
Detection guidance
- Inventory applications and environments that use the Semantic Kernel Python SDK and record the installed package version.
- Identify services that use InMemoryVectorStore, especially those that expose filter functionality to external or untrusted input.
- Monitor application processes for unexpected child processes, network connections or file changes that would be unusual for the service.
Limitations of the available information
The sources do not describe the technical details of the flaw, the exact input conditions, or the full list of affected configurations. Whether public proof-of-concept material exists is unknown from the record. The exact lower bound of affected versions is not stated. The EPSS date in the record should be treated with care when assessing currency of the score.
Frequently asked questions
Which Semantic Kernel versions are affected by CVE-2026-26030?
According to the record, versions before 1.39.4 of the Microsoft Semantic Kernel Python SDK are affected. The lower bound of the affected range is not stated in the available data.
Is CVE-2026-26030 known to be actively exploited?
The record shows the CVE is not listed in the CISA KEV catalog, and no confirmed exploitation appears in the sources consulted.
What should administrators do about this vulnerability?
The vendor advisory recommends upgrading to 1.39.4 or higher. As an interim workaround, avoid using InMemoryVectorStore in production until the update is applied.
This analysis was drafted with AI assistance from verified source data and automatically checked against it.