How severe is GHSA-xjw9-4gw8-4rqx?

GHSA-xjw9-4gw8-4rqx has a CVSS score of 9.9/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by GHSA-xjw9-4gw8-4rqx?

GHSA-xjw9-4gw8-4rqx affects the following packages: semantic-kernel (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-xjw9-4gw8-4rqx?

Update semantic-kernel to 1.39.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xjw9-4gw8-4rqx is resolved across your whole dependency graph.

How do I detect GHSA-xjw9-4gw8-4rqx in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for semantic-kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-xjw9-4gw8-4rqx if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-xjw9-4gw8-4rqx?

O3 pinpoints whether GHSA-xjw9-4gw8-4rqx is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-xjw9-4gw8-4rqx actively exploited in the wild?

No public exploit code has been indexed for GHSA-xjw9-4gw8-4rqx 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 GHSA-xjw9-4gw8-4rqx?

GHSA-xjw9-4gw8-4rqx has an EPSS (Exploit Prediction Scoring System) score of 2.9%, 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 GHSA-xjw9-4gw8-4rqx?

GHSA-xjw9-4gw8-4rqx 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 GHSA-xjw9-4gw8-4rqx published, and has it been updated?

GHSA-xjw9-4gw8-4rqx was published on February 19, 2026 and was last updated on June 8, 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

GHSA-xjw9-4gw8-4rqx

CRITICAL

Microsoft Semantic Kernel InMemoryVectorStore filter functionality vulnerable to remote code execution

Also known asCVE-2026-26030PYSEC-2026-163

Published

Feb 19, 2026

Updated

Jun 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

2.9%probability of exploitation in next 30 days

Lower Risk85th percentile+2.81%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

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

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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update semantic-kernel to 1.39.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xjw9-4gw8-4rqx is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-xjw9-4gw8-4rqx is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-xjw9-4gw8-4rqx. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

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

O3 Security · Impact-Aware SCA

Is GHSA-xjw9-4gw8-4rqx in your dependencies?

O3 detects GHSA-xjw9-4gw8-4rqx across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works