Answer in brief
CVE-2026-39987 records a High severity vulnerability in marimo Affected by Pre-Auth Remote Code Execution via Terminal WebSocket Authentication Bypass. The current sources mark it as known exploited. The current feed maps marimo-team/marimo (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps marimo-team/marimo (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| marimo-team/marimogeneric | < 0.23.0 | Not reported |
Published upstream
Apr 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
May 7, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Apr 23, 2026
Evidence: source:kev:kev:kev:recordmarimo 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.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-39987 records a High severity vulnerability in marimo Affected by Pre-Auth Remote Code Execution via Terminal WebSocket Authentication Bypass. The current sources mark it as known exploited. The current feed maps marimo-team/marimo (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps marimo-team/marimo (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| marimo-team/marimogeneric | < 0.23.0 | Not reported |
Published upstream
Apr 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
May 7, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Apr 23, 2026
Evidence: source:kev:kev:kev:recordmarimo 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.
Quoted source text, attributed separately from HOL analysis.