CVE-2025-66398Public exploitNetwork attack vector

Account takeover via unauthenticated shared restore state

Published Jan 1, 2026 · Updated Jan 1, 2026

State pollution in Signal K Server before 2.19.0 allows remote attackers to overwrite configuration through a hijacked restore. The unauthenticated /skServer/validateBackup endpoint stores an uploaded archive path in the module-global restoreFilePath variable, which /skServer/restore later consumes. Exploitation requires a restore triggered while security is disabled or by an administrator; restored security data enables account takeover, and a separate app-store command injection yields code execution.

CVSS severity9.6
Critical
EPSS probability20.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

State pollution in Signal K Server before 2.19.0 allows remote attackers to overwrite configuration through a hijacked restore. The unauthenticated /skServer/validateBackup endpoint stores an uploaded archive path in the module-global restoreFilePath variable, which /skServer/restore later consumes. Exploitation requires a restore triggered while security is disabled or by an administrator; restored security data enables account takeover, and a separate app-store command injection yields code execution.

The record

CVE
CVE-2025-66398
Published
Jan 1, 2026
Updated
Jan 1, 2026
Vendor
Signal K
Product
Signal K Server
Classifications
CWE-78, CWE-913, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.19.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Signal K · Signal K Serverversion=< 2.19.0

Published CVSS scores

9.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CWE-913Improper Control of Dynamically-Managed Code Resources
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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