Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:L) | Low complexity |
| Attack requirements (AT:N) | No attack requirements |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:N) | No user interaction |
| Confidentiality (VC:N) | No confidentiality impact |
| Integrity (VI:H) | High integrity impact |
| Availability (VA:N) | No availability impact |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
About Signalk Signal K Server
CVE-2026-41893 affects Signalk Signal K Server, a product from Signalk. Before acting, confirm where Signalk Signal K Server runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: Signal K Server is a server application that runs on a central hub in a boat. Prior to version 2.25.0, the HTTP login endpoints (POST /login and POST /signalk/v1/auth/login) are protected by express-rate-limit (default: 100 attempts per 10-minute window, configurable via HTTP_RATE_LIMITS). The WebSocket login path — sending {login: {username, password}} messages over an established WebSocket connection — calls app.securityStrategy.login() directly without any rate limiting. An attacker can bypass HTTP rate limiting entirely by opening a WebSocket connection and attempting unlimited password guesses at the speed bcrypt allows (~20 attempts/sec with 10 salt rounds). This issue has been patched in version 2.25.0.
Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Signalk Signal K Server |
| Affected versions | Signal K Server before 2.25.0 |
| Published | May 9, 2026 |
| Last modified | Jul 24, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | security-advisories@github.com |
How to detect it
- Inventory every instance of Signalk Signal K Server and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Signalk Signal K Server named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Signalk Signal K Server to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
Technical References
Frequently asked questions
Related CVEs
Signal K Server is a server application that runs on a central hub in a boat. Prior to 1.5.0, a command injection vulnerability allows authenticated users with write permissions to execute arbitrary shell commands on the Signal K server when the set-system-time plugin is enabled. Unauthenticated users can also exploit this vulnerability if security is disabled on the Signal K server. This occurs due to unsafe construction of shell commands when processing navigation.datetime values received via WebSocket delta messages. This vulnerability is fixed in 1.5.0.
Signal K Server is a server application that runs on a central hub in a boat. Versions prior to 2.19.0 of the appstore interface allow administrators to install npm packages through a REST API endpoint. While the endpoint validates that the package name exists in the npm registry as a known plugin or webapp, the version parameter accepts arbitrary npm version specifiers including URLs. npm supports installing packages from git repositories, GitHub shorthand syntax, and HTTP/HTTPS URLs pointing to tarballs. When npm installs a package, it can automatically execute any `postinstall` script defined in `package.json`, enabling arbitrary code execution. The vulnerability exists because npm's version specifier syntax is extremely flexible, and the SignalK code passes the version parameter directly to npm without sanitization. An attacker with admin access can install a package from an attacker-controlled source containing a malicious `postinstall` script. Version 2.19.0 contains a patch for the issue.
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.
Databasus 3.7.0 through 3.61.0 contains an authentication bypass vulnerability that allows unauthenticated attackers to brute-force password reset codes via POST /api/v1/users/reset-password. Attackers can request a six-digit code for a known email, then guess it without rate limiting, lockout, or invalidation to take over accounts, including administrators.
Shenzhen Tenda W30E V2 firmware versions up to and including V16.01.0.19(5037) do not enforce rate limiting or account lockout mechanisms on authentication endpoints. This allows attackers to perform unrestricted brute-force attempts against administrative credentials.
Netherman Portal del Hermano (portaldelhermano.es) before 2026-10-06 contains a broken authentication vulnerability in its password-recovery flow at the POST /password/create-access and POST /password/email endpoints, allowing unauthenticated attackers to take over any member account across all tenants by exploiting the lack of rate limiting and distinct error messages that act as oracles for each of the four identity-verification factors (DNI, date of birth, phone number, last four IBAN digits). Attackers can confirm the DNI via the oracle, brute-force the date of birth and IBAN digits, obtain the phone number through open-source intelligence, then submit an attacker-controlled email field so the password reset link is delivered to them, enabling full account takeover including profile data, full IBAN, and fiscal documents.
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