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Fencer Vulns
critical 9.7

CVE-2025-66398 in the critical feed json

Signal K Server has Unauthenticated State Pollution leading to Remote Code Execution (RCE)

published 2026-01-01 10 mo ago modified 2026-10-07 33 d ago also GHSA-w3x5-7c4c-66p9 , EUVD-2025-206140

cvss
9.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
19.9%
EPSS 19.9% chance of exploitation in 30 days, percentile 97%
public exploits
0
none known

Summary

Signal K Server is a server application that runs on a central hub in a boat. Prior to version 2.19.0, an unauthenticated attacker can pollute the internal state (`restoreFilePath`) of the server via the `/skServer/validateBackup` endpoint. This allows the attacker to hijack the administrator's "Restore" functionality to overwrite critical server configuration files (e.g., `security.json`, `package.json`), leading to account takeover and Remote Code Execution (RCE). Version 2.19.0 patches this vulnerability.

Patch / fix

  • npm signalk-server 2.19.0
  • signalk signal_k_server 2.19.0

CISA SSVC

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

Exploit prediction

19.85% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/SignalK/signalk-server/security/advisories/GHSA-w3x5-7c4c-66p9 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.7 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
GitHub 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
npm signalk-server
<2.19.0
2.19.0

Affected products

  • SignalK signalk-server

Classification

Weakness
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command
  • CWE-913 Improper Control of Dynamically-Managed Code Resources

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.