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Exploited vulnerability · CISA KEV

Is CVE-2026-39987 exploited? Yes: in CISA KEV since 23 Apr 2026

Gociux · Marimo · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2026-39987, Marimo Remote Code Execution Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 23 Apr 2026, 14 days after it was published. It affects Marimo. If you run it, CISA's required action is: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

exploitedYesCISA KEV · 23 Apr 2026
ransomwareNot knownno confirmed use
EPSStop 1%among the most likely CVEs to be exploited
severity9.3CVSS 4.0 · critical
US federal due7 May 2026BOD 22-01 deadline

What it is

Marimo contains an pre-authorization remote code execution vulnerability, allowing an unauthenticated attacked to shell access and execute arbitrary system commands.

VendorMarimo (1 exploited CVE in KEV)
ProductMarimo
VulnerabilityMarimo Remote Code Execution Vulnerability
WeaknessCWE-306
Published9 Apr 2026
Added to KEV23 Apr 2026
Reported by (CNA)GitHub_M

What to do

  1. Check whether you run it. Look for Marimo in your asset inventory, including appliances and cloud images. Stack check lists every exploited Marimo CVE at once.
  2. Apply the fix. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 9 Apr 2026.
  4. Get told next time. Email alerts when CISA adds a CVE for Marimo.

References

Questions

Is CVE-2026-39987 being exploited?

Yes. CISA added CVE-2026-39987 to the Known Exploited Vulnerabilities catalog on 23 Apr 2026, which means there is reliable evidence of exploitation in the wild.

Is CVE-2026-39987 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2026-39987?

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Check Marimo's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Marimo and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in April 2026 · act-now radar.

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