CVE-2026-23515: Signal K set-system-time plugin vulnerable to RCE - Command Injection

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 4.6%, percentile 92: FIRST’s model estimates a 4.6% chance of exploitation activity in the next 30 days, higher than 92% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes @signalk/set-system-time (npm) < 1.5.0, fixed in 1.5.0. Check your lockfile, including transitive dependencies.

What it is

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.

From the GitHub advisory

Summary 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.

Details Product: Signal K set-system-time plugin Repository: https://github.com/SignalK/set-system-time

File: index.js, lines 60-71

The vulnerability has three components:

1. Unsanitized Input: The datetime value from navigation.datetime Signal K path is directly interpolated into a shell command without validation 2. Shell Execution: The command is executed via spawn('sh', ['-c', command]), which interprets shell metacharacters 3. Sudo Privileges: The plugin can execute with root privileges if sudo is misconfigured, instructions to limit passwordless sudo to the /bin/date binary helps mitigate this but RCE can still be achieved with the privileges of the user that installed it.

Weakness type: CWE-78.

Product: @signalk/set-system-time (npm) · Assigned by: GitHub_M · Published: 2026-02-02

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 4.59% probability of exploitation activity in the next 30 days; percentile 92.

Timeline

• 2026-02-02 — CVE record published by GitHub_M
• 2026-02-02 — GitHub-reviewed advisory GHSA-p8gp-2w28-mhwg published (critical)
• 2026-02-03 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-p8gp-2w28-mhwg github.com
2. CVE.org record CVE-2026-23515 cve.org
3. NVD entry CVE-2026-23515 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com

Critical npm advisories · Today’s Security Digest