CVE-2026-39987: Marimo Remote Code Execution Vulnerability — CISA KEV Active Exploitation
Marimo contains an pre-authorization remote code execution vulnerability, allowing an unauthenticated attacked to shell access and execute arbitrary system commands.
Confirmed active exploitation. CISA KEV catalog confirmed. Federal agencies must remediate by 2026-05-07. Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
⚠ Intelligence Overview
This critical vulnerability in Marimo Marimo (CVSS 9.5) represents a significant attack surface for threat actors. CYBERDUDEBIVASH SENTINEL APEX assesses exploitation to be technically feasible with moderate effort. Organizations running Marimo in internet-facing or privileged positions face immediate risk. The combination of attack vector, complexity score, and potential impact demands priority-zero remediation.
CISA KNOWN EXPLOITED VULNERABILITY: This vulnerability has been added to the CISA KEV catalog confirming active exploitation. Federal agencies must remediate by 2026-05-07. Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CYBERDUDEBIVASH SENTINEL APEX URGENCY: MAXIMUM. Active exploitation confirmed — treat as active incident requiring immediate response.
🎯 MITRE ATT&CK Mapping
| Category | Mapping |
|---|---|
| Primary Tactic | Execution |
| Primary Technique | T1203 — Exploitation for Client Execution |
| Sub-Technique | T1059 — Command & Scripting Interpreter |
| Weakness (CWE) | See NVD entry |
| Intel Type | 🔴 CVE ANALYSIS |
| Source | cisa_kev |
🔴 CVE Reference
| CVE ID | Reference | Score |
|---|---|---|
| CVE-2026-39987 | NVD → | CVSS 9.5 |
🔍 Detection — Sigma Rule
Deploy across your SIEM (Splunk, Elastic, Microsoft Sentinel, QRadar). SOC Pro subscribers receive pre-compiled SIEM-native query packs.
📡 Detection — YARA Rule
Deploy to endpoint detection tools and threat hunting platforms.
🛡️ SOC Response Playbook
- IMMEDIATE (0-1hr): Identify all instances of Marimo in your environment via asset inventory
- IMMEDIATE (0-1hr): Apply vendor patch — no maintenance window exception
- IMMEDIATE (1-2hr): If no patch: implement WAF rules, ACLs, or compensating controls
- SHORT-TERM (2-4hr): Deploy Sigma detection rule to SIEM — validate alert generation
- SHORT-TERM (4-8hr): Review logs for exploitation indicators
- SHORT-TERM (8-24hr): Hunt for post-exploitation: new accounts, lateral movement, persistence
- MANDATORY: CISA KEV deadline 2026-05-07 — document remediation for compliance
- ONGOING: Subscribe to Marimo security advisories for follow-on patches
📎 Intelligence References
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Report ID: SENTINEL-CVE-2026-39987-2026-04-27 — Source: cisa_kev
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