Skip to content
Fencer Vulns
medium 5.0

CVE-2026-58057 json

Flowise - Custom MCP Environment Variable Denylist Bypass via Case Sensitivity

published 2026-06-28 4 mo ago modified 2026-11-08 27 h ago also EUVD-2026-39977

cvss
5.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
1
Exploit-DB

Summary

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.

Patch / fix

  • Flowise Flowise 3.1.3

Timeline

  1. Published
  2. First public exploit (EDB-52623)

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

1.56% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-52623 Flowise 3.1.3 - arbitrary code execution webapps, 2026-07-07
  • vulncheck.com https://www.vulncheck.com/advisories/flowise-custom-mcp-environment-variable-denylist-bypass-via-case-sensitivity referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/bikini/exploitarium/tree/main/flowise-mcp-env-case-bypass-poc referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.0 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
CNA 4.0 2.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
CNA 4.0 2.3 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/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

Affected products

  • Flowise Flowise

Classification

Weakness
  • CWE-178 Improper Handling of Case Sensitivity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.