How severe is CVE-2026-25592?

CVE-2026-25592 has a CVSS score of 9.9/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-25592?

CVE-2026-25592 affects the following packages: Microsoft.SemanticKernel.Core (NuGet), semantic-kernel (PyPI). Ecosystems affected: NuGet, PyPI.

How do I fix CVE-2026-25592?

Update Microsoft.SemanticKernel.Core to 1.71.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-25592 is resolved across your whole dependency graph.

How do I detect CVE-2026-25592 in my NuGet, PyPI dependencies?

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

How do I mitigate CVE-2026-25592 if there is no patch (or I can't update yet)?

Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Is CVE-2026-25592 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-25592 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-2026-25592?

CVE-2026-25592 has an EPSS (Exploit Prediction Scoring System) score of 2.5%, placing it in the 85th 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-2026-25592?

CVE-2026-25592 is classified as Path Traversal (CWE-22). 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-2026-25592 published, and has it been updated?

CVE-2026-25592 was published on February 6, 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.

.NET

.NET NuGet🐍 PyPI

Not in CISA KEV

CRITICAL severity

CVE-2026-25592 — Microsoft.SemanticKernel.…

CRITICALFix: microsoft/semantic-kernel#13478

CVE-2026-25592 is a critical-severity (CVSS 9.9) Path Traversal vulnerability in Microsoft.SemanticKernel.Core. A fix is available for Microsoft.SemanticKernel.Core — see the affected versions and patch details below.

Semantic Kernel has an Arbitrary File Write via AI Agent Function Calling in .NET SDK

Also known asGHSA-2ww3-72rp-wpp4PYSEC-2026-531

Published

Feb 6, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 5, 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-2026-25592.

EPSS Exploitation Probability

via FIRST.org ↗

2.5%probability of exploitation in next 30 days

Lower Risk-0.04%

Lower risk than most CVEs85th percentile — riskier than 85% 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

2 pkgs affected

.NETMicrosoft.SemanticKernel.Core🐍semantic-kernel

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

Description

Impact

What kind of vulnerability is it? Who is impacted? An Arbitrary File Write vulnerability has been identified in Microsoft's Semantic Kernel .NET SDK, specifically within the SessionsPythonPlugin. Developers who have built applications which include Microsoft's Semantic Kernel .NET SDK and are using the SessionsPythonPlugin

Patches

Has the problem been patched? What versions should users upgrade to? The problem has been fixed in Microsoft.SemanticKernel.Plugins.Core version 1.71.0. Users should upgrade to version 1.71.0 or higher.

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading? Users can create a Function Invocation Filter which checks the arguments being passed to any calls to DownloadFileAsync  or UploadFileAsync and ensures the provided localFilePath is allow listed.

References

Are there any links users can visit to find out more?

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
.NETNuGet	`Microsoft.SemanticKernel.Core`	all versions	1.71.0`dotnet add package Microsoft.SemanticKernel.Core --version 1.71.0`
🐍PyPI	`semantic-kernel`	all versions	1.39.3`pip install --upgrade 'semantic-kernel==1.39.3'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.SemanticKernel.Core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Microsoft.SemanticKernel.Core to 1.71.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-25592 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

### Impact _What kind of vulnerability is it? Who is impacted?_ An Arbitrary File Write vulnerability has been identified in Microsoft's Semantic Kernel .NET SDK, specifically within the `SessionsPythonPlugin`. Developers who have built applications which include Microsoft's Semantic Kernel .NET SDK and are using the `SessionsPythonPlugin` ### Patches _Has the problem been patched? What versions should users upgrade to?_ The problem has been fixed in [Microsoft.SemanticKernel.Plugins.Core version 1.71.0](https://www.nuget.org/packages/Microsoft.SemanticKernel.Plugins.Core/1.71.0). Users shoul