What is CVE-2026-26030?
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.
The record classifies CVE-2026-26030 under weakness class CWE-94. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 252 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 10 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - EPSS (FIRST)
- 3.7% probability of exploitation in the next 30 days, higher than 89.7% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 10/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-02-19, last modified 2026-02-26
Is CVE-2026-26030 being exploited?
Weaponised exploit code for CVE-2026-26030 is publicly available. 2 public proof-of-concept repositories are tracked for this identifier. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.
Affected products and versions
- microsoft: semantic-kernel
How to fix CVE-2026-26030
No vendor patch reference has been recorded for CVE-2026-26030 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-26030
2 tracked threats in the Threadlinqs corpus reference CVE-2026-26030, either in the campaign’s CVE list or as an indicator on the campaign record.
- Microsoft Semantic Kernel Prompt-Injection-to-RCE & Arbitrary File Write — CVE-2026-26030 (InMemoryVectorStore eval) + CVE-2026-25592 (SessionsPythonPlugin) — CRITICAL · 2026-05-09
- Microsoft Semantic Kernel — Critical RCE & Arbitrary File Write Chain (CVE-2026-26030, CVE-2026-25592) — CRITICAL · 2026-05-08
Sources
Enriched from CVE.org, FIRST EPSS, public proof-of-concept repositories. Last verified by Threadlinqs on .