Overview
CVE-2026-39987 has been added to the CISA Known Exploited Vulnerabilities catalog. Published on April 09, 2026. Threat actors are actively exploiting this vulnerability in real-world attacks.
marimo is a reactive Python notebook.
Threat Intelligence
| Metric | Value |
|---|---|
| CVE ID | CVE-2026-39987 |
| Severity | HIGH |
| CVSS Score | 0.0/10 |
| CISA KEV | ✅ Yes — Actively Exploited |
| KEV Date Added | April 23, 2026 |
| Remediation Deadline | May 07, 2026 |
| EPSS Score | 95.6% exploit probability |
| EPSS Percentile | Top 99% of all CVEs |
Why This Matters
This vulnerability has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog, which means threat actors are actively exploiting it in real-world attacks.
Federal agencies are required to remediate by May 07, 2026. All organizations should treat this deadline as a strong recommendation.
Exploit Prediction (EPSS)
The FIRST EPSS model rates this vulnerability at 95.6% exploit probability (Very High). This places it in the top 99% of all known CVEs by likelihood of exploitation in the next 30 days.
EPSS (Exploit Prediction Scoring System) uses real-world exploit data and machine learning to predict whether a vulnerability will be exploited. A high EPSS score is a strong signal to prioritize remediation.
Recommended Actions
- Verify exposure — Determine if your environment uses the affected software.
- Apply patches — Update to the latest version as soon as a fix is available.
- Monitor for compromise — Check logs for unusual activity.
- Meet the deadline — CISA recommends remediation by May 07, 2026.
References
CVE data aggregated from the National Vulnerability Database (NVD), CISA Known Exploited Vulnerabilities catalog, and FIRST EPSS. Analysis updated as new intelligence becomes available. Last updated: 2026-04-23.