CVE-2026-55591
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.
Does this matter?
Lower severity and a low EPSS score (0.30%). Track it; it rarely justifies an emergency change on its own.
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 3.1
- 5.8 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
- EPSS
- 0.30% probability · 22th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-918
- Source
- security-advisories@github.com
EPSS 0.3% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.