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CVE-2026-58057

Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity

No known exploitation. EPSS puts it in the 75th percentile. Fixed in 3.1.3.

CVSS 3.15.0MediumEPSS percentile75th1.6% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
No public exploit knownFix3.1.3Upgrade to this build

Published Updated Sources: CVE.org, NVD

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • FlowiseAffected: < 3.1.3Upgrade to: 3.1.3Stated by: CVE record
  • Flowiseai FlowiseAffected: < 3.1.3Upgrade to: 3.1.3Stated by: NVD

Versions as the sources state them. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Flowise before 3.1.3 validates Custom MCP stdio environment variables against a denylist using a case-sensitive comparison, so on Windows, where environment names are case-insensitive, supplying 'node_options' bypasses the NODE_OPTIONS denylist entry. An authenticated user who can configure a Custom MCP node can thereby inject NODE_OPTIONS --require and execute arbitrary code in the Flowise server context.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS75th
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

1.6% chance of exploitation activity in the next 30 days, which ranks it in the 75th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

6 events over 11 days, from the signal feeds we watch.

  1. Patch availablerecord updated
  2. Record updated
  3. Publishedweakness classified
  4. OpenVAS check added

Affected products

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

Scored 5.0 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality LowSome restricted information is disclosed, but limited in scope
  • Integrity LowData modification is possible but limited in scope or consequence
  • Availability LowReduced performance or intermittent disruption of service

Weaknesses

Sources

References in the record

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We'll flag the next CVE, public exploit or patch for Flowise, not every advisory.