{"cve":"CVE-2026-55591","nvd":{"published":"2026-09-15T16:17:14.703","modified":"2026-09-30T17:51:56.193","status":"Deferred","description":"Signal K Server is a server application that runs on a central hub in a boat. Prior to 2.28.0, makeRemoteRequest() in src/serverroutes.ts accepted attacker-controlled host, port, useTLS, and selfsignedcert parameters from the testSignalKConnection, requestAccess, and checkAccessRequest endpoints without validating the destination. When security was not configured, addAdminMiddleware() was a no-op in dummysecurity.ts, leaving all three endpoints accessible without authentication. The server could be forced to contact loopback, private, link-local, cloud metadata, or arbitrary external destinations, and selfsignedcert could disable certificate verification for outbound HTTPS requests. The checkAccessRequest endpoint also interpolated requestId into its destination path, allowing traversal to other paths on the selected host. Distinct success, connection-refused, and timeout responses enabled internal port scanning; returned response bodies enabled cloud metadata and internal-service data exfiltration; requestAccess enabled server-side POST requests with attacker-controlled JSON; and access to cluster-internal services could support lateral movement. This issue is fixed in version 2.28.0.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N","score":5.8},"cwes":["CWE-918"],"references":["https://github.com/SignalK/signalk-server/commit/2816b0dda1bdde893d85c969a9c5950e7825eee7","https://github.com/SignalK/signalk-server/releases/tag/v2.28.0","https://github.com/SignalK/signalk-server/security/advisories/GHSA-q59x-jc9f-gfqf","https://github.com/SignalK/signalk-server/security/advisories/GHSA-q59x-jc9f-gfqf"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:53:43.293028046+00:00"},"epss":{"cve":"CVE-2026-55591","score":0.00298,"percentile":0.22231,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-q59x-jc9f-gfqf","url":"https://osv.dev/vulnerability/GHSA-q59x-jc9f-gfqf","summary":"Signal K Server: Server-Side Request Forgery via Remote Connection Endpoints","modified":"2026-06-18T21:41:26.036368Z","packages":[{"ecosystem":"npm","name":"signalk-server","purl":"pkg:npm/signalk-server","ranges":["<2.28.0"],"fixed":["2.28.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}