CVE-2026-39987: in the CISA KEV catalogue

Marimo Remote Code Execution Vulnerability. CISA added CVE-2026-39987 to the Known Exploited Vulnerabilities catalogue on 2026-04-23 with a default due date of 2026-05-07. Known ransomware campaign use: Unknown. Forensic triage flag: No.

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

Vendor / product: Marimo Marimo
CWE: CWE-306
CISA 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.
EPSS: 100%, percentile 99 (scored 2026-11-03)

EPSS puts nearly every time in 100 odds (100%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.

Vendor and reference links (from CISA)

Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.

Data dates. CISA KEV catalogue version 2026.11.03, released 2026-11-03, 1,767 entries (checked 2026-11-03). EPSS model v2026.06.15, scored 2026-11-03, 399,388 CVEs. Sources: CISA and FIRST (EPSS by FIRST; scores generated by Empirical Security). Copied to our own database and refreshed automatically; if a refresh fails, the previous copy keeps serving with its own date.

Frequently asked questions

Is CVE-2026-39987 in the CISA KEV catalogue?

Yes. CISA added CVE-2026-39987 (Marimo Remote Code Execution Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2026-04-23. CISA's default due date for it is 2026-05-07.

Is CVE-2026-39987 used in ransomware attacks?

CISA marks known ransomware campaign use as Unknown for CVE-2026-39987. That means CISA lacks confirmation, not that ransomware groups do not use it.

What should I do about CVE-2026-39987?

CISA's 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.

Sources

CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
NVD record for CVE-2026-39987