CVE-2026-39320 is a high-severity vulnerability affecting SignalK Server, which is a server application that operates as a central hub in a boat. The vulnerability arises from an unauthenticated Regular Expression Denial of Service (ReDoS) attack within the WebSocket subscription handling logic. Specifically, versions prior to 2.25.0 are susceptible to this attack, which can lead to severe performance degradation.
The vulnerability allows an attacker to inject unescaped regex metacharacters into the `context` parameter of a stream subscription. This manipulation can cause the server's Node.js event loop to enter a catastrophic backtracking loop while evaluating long string identifiers, such as the server's self UUID. Consequently, this results in a complete Denial of Service (DoS) where the server's CPU usage spikes to 100%, rendering it unresponsive to further API or socket requests.
The CVSS score for this vulnerability is 7.5, indicating high severity. This score underscores the importance of immediate action to mitigate the risk posed by this vulnerability. Organizations using affected versions should prioritize patching to version 2.25.0, which addresses this issue.
Given the impact on availability, organizations should consider this vulnerability critical in their risk management strategies. With the potential for significant service disruption, swift remediation is necessary to maintain operational integrity.
Vulnerability Details
The official description of this vulnerability states that versions prior to 2.25.0 of Signal K Server are vulnerable to an unauthenticated Regular Expression Denial of Service (ReDoS) attack. The CVSS score is 7.5, reflecting a high severity level as it allows for significant disruption of service.
The vulnerability affects the Signal K Server component specifically. The problem was disclosed on April 21, 2026, with a patch released in version 2.25.0. The Common Weakness Enumeration (CWE) classifications for this vulnerability include CWE-400 (Uncontrolled Resource Consumption) and CWE-1333 (Improper Regular Expression Implementation).
Technical Analysis
The root cause of CVE-2026-39320 lies in the way Signal K Server handles input for WebSocket subscriptions. The application fails to properly sanitize user input, allowing attackers to exploit this weakness through crafted requests containing regex metacharacters.
The attack vector is network-based, requiring no privileges or user interaction to execute. Attack complexity is low, making it easy for attackers to exploit this vulnerability. Once exploited, the vulnerability can severely impact the availability of the server, as it results in a complete DoS condition.
The confidentiality and integrity impacts are rated as none, indicating that the vulnerability does not facilitate unauthorized data access or modification. However, the availability impact is high, which is critical for organizations relying on real-time data from the Signal K Server.
Risk & Impact Analysis
The risk to organizations includes potential service outages that could disrupt operations relying on Signal K Server for data processing and communication. Given the high availability impact, the vulnerability poses a significant threat to organizations operating maritime applications or services.
Organizations should assess their deployment of Signal K Server and prioritize remediation efforts, particularly for those using versions prior to 2.25.0. The urgency is heightened due to the simplicity of exploitation and the potential for widespread service disruption.
As of now, there is no known active exploitation of this vulnerability, and no public proof of concept has been confirmed. This provides a narrow window for organizations to implement the necessary patches before the vulnerability is potentially exploited in the wild.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions of Signal K Server prior to 2.25.0 are affected by this vulnerability. Organizations should ensure they upgrade to version 2.25.0 or later to mitigate the risk of exploitation.
Mitigation & Remediation
To remediate this vulnerability, organizations should upgrade Signal K Server to version 2.25.0 or later, which includes the necessary fixes for this issue. For those unable to perform an immediate upgrade, implementing rate limiting on WebSocket connections may provide a temporary mitigation strategy.
Further, organizations should consider enhancing their application security posture by conducting regular security assessments and penetration testing. This can help identify similar vulnerabilities before they can be exploited.
For a more comprehensive approach, organizations can leverage penetration testing and continuous monitoring strategies to maintain the security of their systems.
Detection Guidance
Organizations should monitor logs for unusual spikes in CPU usage or performance degradation associated with the Signal K Server. Additionally, behavioral anomalies in WebSocket connections should be investigated to determine if they correlate with the vulnerability.
Network signatures can also be established to identify potentially malicious requests that may be attempting to exploit this vulnerability. Regular reviews of system changes and configurations can help maintain awareness of potential threats.
AppSecure Threat Intelligence Insight
The emergence of CVE-2026-39320 highlights a critical area in application security concerning the handling of user input. As organizations increasingly rely on server applications for operational data, vulnerabilities like these can lead to significant downtimes and service disruptions.
This vulnerability exemplifies the need for comprehensive input validation and security mechanisms, particularly in applications exposed to the internet. As such, security teams should prioritize regular updates and rigorous testing of their systems.
To further enhance security, organizations may consider implementing application security assessments and integrating security into their development lifecycle.
Security practitioners should stay informed about similar trends and vulnerabilities by engaging with the community and reviewing insights on penetration testing methodologies to enhance their defensive strategies.
Finally, the importance of ongoing education and awareness cannot be overstated. Security teams should engage in continuous learning regarding vulnerabilities and mitigation strategies to ensure robust defenses against emerging threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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