High Injection exploit reference

CVE-2025-66398 — Signal K Server has Unauthenticated State Pollution leading to Remote Code Execution (RCE)

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.

Published Jan 1, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Moderate

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 19.9% (30-day exploitation probability)+15
Technical severity (high)+6
CISA SSVC: exploitation "poc"+5
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

19.85%

ahead of 97% of scored CVEs · Oct 14, 2026

Affects

Signalk

Signal K Server

CVSS base

8.8

High · 3 source(s)

Prioritization reference: 9.7 provisional

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Signalk Signal K Server).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Exploitation requires user interaction: tighten email/web filtering and warn affected users.
EPSS ahead of 97% of scored CVEs: prioritize it in the patch queue.
Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Signalk	Signal K Server	< 2.19.0	Vulnerable	NIST National Vulnerability Database
Signalk	Signal K Server	version < 2.19.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.7	CVSS 3.1	Critical	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
9.6	CVSS 3.1	Critical	2.8	6.0	security-advisories@github.com via NIST National Vulnerability Database
8.8	CVSS 3.1	High	2.8	5.9	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 9.7 (GitHub_M via CVE Program (cve.org) e CISA ADP) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-78 · OS Command Injection

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 19.85%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Look for parameters with command/query metacharacters and unexpected child processes of the service.

web/proxy/WAF logsnetwork IDS/IPSapplication logsendpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · signalk/signalk-server
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 8.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Jan 1, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

2 on the record

github.com/SignalK/signalk-server/security/advisories/GHSA-w3x5-7c4c-66p9
Exploit, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
github.com/SignalK/signalk-server/releases/tag/v2.19.0
Release Notes, x_refsource_MISC, NIST National Vulnerability Database

Elsewhere on this site

Signalk
every CVE for this vendor

Injection
same class

CWE-78
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-55591 Signal K Server: Server-Side Request Forgery via Remote Connection Endpoints Sep 15, 2026
High CVE-2026-41893 Signal K Server's WebSocket Login Endpoint Lacks Rate Limiting (Credential Brute-Force) May 9, 2026
High CVE-2026-39320 Signal K Server has an Unauthenticated Regular Expression Denial of Service (ReDoS) via WebSocket Subscription Paths Apr 20, 2026
Medium CVE-2026-35038 signalk-server: Arbitrary Prototype Read via `from` Field Bypass Apr 2, 2026
Medium CVE-2026-34083 signalk-server: OAuth Authorization Code Theft via Unvalidated Host Header in OIDC Flow Apr 2, 2026
High CVE-2026-33951 signalk-server: Unauthenticated Source Priorities Manipulation Apr 2, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-66398 is "Signal K Server has Unauthenticated State Pollution leading to Remote Code Execution (RCE)", rated High. It affects Signal K Server (Signalk); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.8 describes technical severity. EPSS 19.85% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.