CVE-2026-39987

Marimo: Remote Code Execution

As of , CVE-2026-39987 in Marimo is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch soon.

Exploited
Yes: CISA listed it on 23 April 2026
US federal deadline
7 May 202614 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.38Higher than 98% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
Public exploit
1 Exploit-DB entry
Fix
Vendor advice: github.comLinks below, from CISA's entry.

What CISA says to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

CISA's required action

What the flaw is

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

CISA's description

marimo is a reactive Python notebook. Prior to 0.23.0, Marimo has a Pre-Auth RCE vulnerability. The terminal WebSocket endpoint /terminal/ws lacks authentication validation, allowing an unauthenticated attacker to obtain a full PTY shell and execute arbitrary system commands. Unlike other WebSocket endpoints (e.g., /ws) that correctly call validate_auth() for authentication, the /terminal/ws endpoint only checks the running mode and platform support before accepting connections, completely skipping authentication verification. This vulnerability is fixed in 0.23.0.

The CVE record's description, from GitHub_M

CVE published
9 April 2026
Assigned by
GitHub_M
CVSS
9.3 Critical (CVSS 4.0, from the CNA)
CWE-306
Missing Authentication for Critical Function
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.
  4. Exploit-DB published an exploit (EDB-ID 52673).

Public exploits

Facts from Metasploit's module list and Exploit-DB's index; we never copy exploit code.

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