CASCACascade Atlas

Evidence dossier

CVE-2026-39987

marimo Affected by Pre-Auth Remote Code Execution via Terminal WebSocket Authentication Bypass

82.8–99.1Priority evidence range
As known Jul 19, 2026, 5:00 AM UTCgen-56ccdaf9

Normalized restatement

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.

State
PUBLISHED
Published
Apr 9, 2026
Updated
Apr 24, 2026
Evidence coverage
85%
CISA KEVCatalog member

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

FIRST EPSS95.64%

2026-07-18 · v2026.06.15 · percentile 99.9%

Source stateNo scored conflict

Distinct CVSS assessments remain side by side; none are averaged.

Source comparison

Who said what

CISA-ADPindependent enrichment
container

CISA ADP Vulnrichment

GitHub_Moriginal assertion
container

marimo Affected by Pre-Auth Remote Code Execution via Terminal WebSocket Authentication Bypass

CISA KEVoriginal assertion
observed_exploitation

Marimo Remote Code Execution Vulnerability

FIRST EPSSoriginal assertion
model_probability

Probability 0.956450000000; percentile 0.998620000000

Applicability

Cited product scope

Trace impact →
marimo-teammarimo
[{"status": "affected", "version": "< 0.23.0"}]unknown
Unknown vendorUnknown product
cpe:2.3:a:coreweave:marimo:*:*:*:*:*:python:*:*; end excluding 0.23.0supported

Assessments

CVSS by origin

9.8
nvd@nist.govCVSS 3.1 · role PrimaryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3
security-advisories@github.comCVSS 4.0 · role SecondaryCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
9.3
GitHub_MCVSS 4.0 · role unknownCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Limitations and unknowns

  • KEV membership is authoritative for the catalog, not proof of exposure in any environment.
  • EPSS is a dated model probability and not an individual-environment prediction.
  • Affected or fixed status applies only to the exact cited product and version scope; unresolved scope remains unknown.
  • NVD-carried upstream facts remain derivative and are not independent corroboration.
  • Only NVD metrics validated under the generation-bound calculator are Public Priority eligible; direct CVE record metrics remain display-only.
  • NVD CVSS source eligibility is closed: NVD-authored, exact record-source, or registered same-CVE container origin; unmapped sources remain display-only.
  • Factor D is unknown in Public Core because no accepted canonical mapping-obligation ledger is present.
  • Core replay supports the active and immediately prior generation; retrospective valid-at replay is deferred.