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Microsoft Semantic Kernel InMemoryVectorStore filter functionality vulnerable to remote code execution

Critical severity GitHub Reviewed Published Feb 19, 2026 in microsoft/semantic-kernel • Updated Jun 8, 2026

Package

pip semantic-kernel (pip)

Affected versions

< 1.39.4

Patched versions

1.39.4

Description

Impact:

An RCE vulnerability has been identified in Microsoft Semantic Kernel Python SDK, specifically within the InMemoryVectorStore filter functionality.

Patches:

The problem has been fixed in python-1.39.4. Users should upgrade this version or higher.

Workarounds:

Avoid using InMemoryVectorStore for production scenarios.

References:

Release python-1.39.4 · microsoft/semantic-kernel · GitHub
PR to block use of dangerous attribute names that must not be accessed in filter expressions

References

@markwallace-microsoft markwallace-microsoft published to microsoft/semantic-kernel Feb 19, 2026
Published by the National Vulnerability Database Feb 19, 2026
Published to the GitHub Advisory Database Feb 19, 2026
Reviewed Feb 19, 2026
Last updated Jun 8, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(28th percentile)

Weaknesses

Improper Control of Generation of Code ('Code Injection')

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. Learn more on MITRE.

CVE ID

CVE-2026-26030

GHSA ID

GHSA-xjw9-4gw8-4rqx

Source code

Credits

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