How severe is CVE-2026-26030?

CVE-2026-26030 has a CVSS score of 9.9/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-26030?

CVE-2026-26030 affects the following packages: semantic-kernel (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-26030?

Update semantic-kernel to 1.39.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-26030 is resolved across your whole dependency graph.

How do I detect CVE-2026-26030 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for semantic-kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-26030 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2026-26030 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-26030 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-26030?

CVE-2026-26030 has an EPSS (Exploit Prediction Scoring System) score of 3.9%, placing it in the 90th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-26030?

CVE-2026-26030 is classified as Code Injection (CWE-94). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-26030 published, and has it been updated?

CVE-2026-26030 was published on February 19, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

CRITICAL severity

CVE-2026-26030 — semantic-kernel

CRITICALFix: microsoft/semantic-kernel#13505

CVE-2026-26030 is a critical-severity (CVSS 9.9) Code Injection vulnerability in semantic-kernel. A fix is available for semantic-kernel — see the affected versions and patch details below.

Microsoft Semantic Kernel InMemoryVectorStore filter functionality vulnerable to remote code execution

Also known asGHSA-xjw9-4gw8-4rqxPYSEC-2026-163

Published

Feb 19, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-26030.

EPSS Exploitation Probability

via FIRST.org ↗

3.9%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs90th percentile — riskier than 90% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐍semantic-kernel

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`semantic-kernel`	all versions	1.39.4`pip install --upgrade 'semantic-kernel==1.39.4'`

Affected Products

1 product · 1 configurations

Application

semantic kernelmicrosoft

< 1.39.4

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for semantic-kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update semantic-kernel to 1.39.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-26030 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Frequently Asked Questions

### 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](https://github.com/microsoft/semantic-kernel/releases/tag/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](https://github.com/microsoft/semantic-kernel/releases/tag/python-1.39.4) [PR to block use of dangerous