How severe is CVE-2025-66398?

CVE-2025-66398 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-66398 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 18% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66398?

CVE-2025-66398 affects Signalk Signal K Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66398?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2025-66398 have an EU (EUVD) identifier?

Yes. CVE-2025-66398 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-206140.

When was CVE-2025-66398 published?

CVE-2025-66398 was published on 2026-01-01 and last updated on 2026-06-17.

CVE-2025-66398

CVE-2025-66398 is a critical-severity vulnerability in Signalk Signal K Server with a CVSS 3.x base score of 9.6. Its EPSS exploit-prediction score of 18% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-78.

Key facts

Severity: Critical (CVSS 3.x base score 9.6)
EPSS exploit prediction: 18% (97th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-206140
Weakness: CWE-78
Affected product: Signalk Signal K Server
Published: 2026-01-01
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2025-66398?: 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.
How severe is CVE-2025-66398?: CVE-2025-66398 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-66398 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 18% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66398?: CVE-2025-66398 affects Signalk Signal K Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66398?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2025-66398 have an EU (EUVD) identifier?: Yes. CVE-2025-66398 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-206140.
When was CVE-2025-66398 published?: CVE-2025-66398 was published on 2026-01-01 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:signalk:signal_k_server:*:*:*:*:*:*:*:*

More vulnerabilities in Signalk Signal K Server

CVE-2026-23515 — Critical (CVSS 9.9): Signal K Server is a server application that runs on a central hub in a boat. Prior to 1.5.0, a command injection…
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