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Fencer Vulns
critical 9.8

CVE-2026-18482 json

CVE-2026-18482

published 2026-08-20 2 mo ago modified 2026-09-03 2 mo ago also EUVD-2026-63326

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.4%
EPSS 3.4% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

Neo.mjs contains a command injection vulnerability within the FileSystemService.mjs component of the ai/mcp/server/file-system MCP server, where the checkSyntax() and runPlaywrightTest() functions unsafely interpolate caller-controlled absolutePath values into shell commands, enabling arbitrary OS command execution when an AI agent is induced to invoke these tools. Commit 88c77fc fixes these vulnerabilities.

Patch / fix

  • Klarso GmbH neo-mjs 88c77fc4

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
2 mo ago

Exploit prediction

3.43% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • novice-22.com https://novice-22.com/posts/neo-mjs/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Klarso GmbH neo-mjs

Classification

Weakness
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command

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.