Critical Cybersecurity Vulnerabilities in Kaleris Navis N4 Terminal Operating System Disrupting Global Ports

Shipping ports around the world increasingly depend on complex software to keep cargo—and commerce—moving. The Kaleris Navis N4 Terminal Operating System, a mainstay in global terminal operations, recently landed in the cybersecurity spotlight due to two critical vulnerabilities that place both operations and sensitive data at substantial risk. As global trade remains a tempting target for cyber actors, the wake-up call for port authorities, system administrators, and the wider maritime sector is stark: digital vulnerabilities at the heart of physical logistics are no longer theoretical concerns but urgent realities requiring decisive action.

The Kaleris Navis N4: Backbone of Modern Terminal Operations​

Kaleris (formerly Navis, now under the Kaleris brand) is a U.S.-headquartered technology vendor that provides advanced software solutions to container terminals and cargo-centric supply chain hubs internationally. The Navis N4 Terminal Operating System (TOS) streamlines the complex interactions involved in vessel berthing, cargo movement, yard planning, and gate processing. These systems provide critical capabilities for automating logistics, managing resources, integrating with port equipment, optimizing efficiency, and maintaining business continuity at mega-terminals—making them foundational to the global supply chain.
With deployment in a majority of top-tier global terminals across every continent, N4’s seamless interoperability and real-time data sharing have become crucial for efficient maritime trade. It is precisely this widespread reliance—and the criticality of the data it stewards—that makes recent security advisories particularly concerning.

Dissecting the Vulnerabilities: A Deep Dive​

Two significant vulnerabilities disclosed in the N4 TOS—tracked as CVE-2025-2566 (Unsafe Java Deserialization) and CVE-2025-5087 (Cleartext Transmission of Sensitive Information)—have placed the system’s reputation for reliability under scrutiny. Each holds profound implications for how ports approach not only TOS infrastructure but also broader operational technologies.

CVE-2025-2566: Unsafe Java Deserialization (CWE-502)​

The first and highest-impact vulnerability involves unsafe Java deserialization present in the Ultra Light Client (ULC) component of older N4 versions. Deserialization allows an application to reconstruct objects from a data stream—an essential part of distributed computing in Java-based architectures. But when deserialization is performed on untrusted data without extensive validation or restriction, attackers can craft malicious requests that, when deserialized by the server, permit arbitrary code execution. In effect, a remote, unauthenticated adversary could potentially gain the same privileges as the application server itself—putting at risk not only data but the operational fabric of the terminal.
According to the official CVE record and corroborating advisories from CISA and independent ICS/OT security practitioners, CVE-2025-2566 yields a CVSS v4 base score of 9.3 (Critical), with the following attack vector:
AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
This vector emphasizes that no privileges or user interaction are required for exploitation and that the outcome can yield high confidentiality, integrity, and availability impacts. Notably, the same issue garners a CVSS v3.1 score of 9.8, underscoring the consensus on criticality across multiple risk frameworks.

CVE-2025-5087: Cleartext Transmission of Sensitive Information (CWE-319)​

A second, related vulnerability addresses a situation where N4 Ultra Light Client communications take place over HTTP using zlib-compressed data, rather than fully encrypted HTTPS/TLS transmissions. This means that credentials and other sensitive information are transmitted in plaintext—albeit compressed—making them readable to any party with network access capable of inspecting traffic between clients and the server.
The practical upshot is straightforward but devastating: an attacker able to capture traffic can extract credentials and operational data, leading to further cascades of compromise. With a CVSS v4 score of 6.0 (High), this vulnerability is markedly easier to exploit in environments where proper network segmentation and encryption are absent.

Scope of Exposure: Global Ports and Critical Infrastructure​

The significance of the Navis N4 vulnerabilities extends well beyond an individual port. The TOS is a mainstay in the transportation systems sector, classified as critical infrastructure across North America, EMEA, APAC, and Latin America. Its deployment footprint includes some of the world’s largest transshipment hubs, frequently situated near urban population centers and serving as lynchpins in national trade.
Notably, the identified vulnerabilities afflict all versions of Navis N4 prior to version 4.0—a span that covers a significant installed base. While the company has aggressively advised its clients and worked to notify all users, the reality is that staggered upgrade cycles, legacy system constraints, and the challenges of maintaining 24/7 operations mean that many ports may still be running exposed versions months after public disclosure.

Potential Impact: From Data Breach to Operational Paralysis​

The real-world consequences of exploiting these vulnerabilities are severe and multifaceted:

• Remote Code Execution (RCE): The ability to execute arbitrary code on core infrastructure could allow attackers to install malicious software (such as ransomware or backdoors), manipulate operational data, or disrupt logistics in ways that directly impact the flow of goods.
• Credential Theft: The compromise of plaintext credentials could grant persistent, unauthorized access to networks and sensitive port operations, circumventing physical security entirely.
• Data Manipulation and Exfiltration: The potential to intercept or alter logistics data could disrupt vessel scheduling, yard planning, customs processing, and billing operations—all of which rely on the integrity and privacy of transactional information.
• Broader Supply Chain Disruption: Ports are highly interconnected; a compromise at a single node has ripple effects both upstream and downstream, with impacts magnified in just-in-time supply networks.

Unpacking the Attack Surface​

Publicly available details suggest that both vulnerabilities are remotely exploitable with low attack complexity and no authentication required. This places them in a category of threats routinely targeted by both financially motivated cybercriminals and nation-state actors interested in disrupting critical infrastructure.
Further, historical campaigns against maritime and ICS networks (including attacks such as NotPetya, which heavily impacted the shipping sector in 2017) have demonstrated the catastrophic kinetic and business consequences resulting from IT system outages. While there is currently no evidence of exploitation in the wild, all technical factors align with threat actor patterns of behavior for post-disclosure exploitation—especially given the high profile and economic value of port operations.

Kaleris Response: Mitigation and Guidance​

Upon discovery, Kaleris moved quickly to assess, report, and mitigate the issues, working directly with CISA (Cybersecurity and Infrastructure Security Agency) to publish comprehensive guidance. Recommended mitigations are stratified according to system version and the specific exposure scenario.

Targeted Version Upgrades​

While the most comprehensive fix involves upgrading to Navis N4 version 4.0 (where ULC has been replaced with a new HTML UI architecture), Kaleris has also released hotfixes for the affected product lines:

• Navis N4: Version 3.1.44+
• Navis N4: Version 3.2.26+
• Navis N4: Version 3.3.27+
• Navis N4: Version 3.4.25+
• Navis N4: Version 3.5.18+
• Navis N4: Version 3.6.14+
• Navis N4: Version 3.7.0+
• Navis N4: Version 3.8.0+

Upgrading to these or later releases is strongly recommended whenever compatible with operational requirements.

Defense-in-Depth and Interim Safeguards​

For ports unable to immediately upgrade—an unfortunately common scenario in the OT world—Kaleris and CISA provide a layered set of risk-mitigation strategies:

• Network Segmentation: N4 systems that do not require internet exposure should be strictly shielded behind firewalls, segmented from business and public-facing networks.
• ULC Disablement: For environments requiring internet exposure, the Ultra Light Client can be disabled at the load balancer, firewall, or application level (by filtering URL patterns or adjusting deployment descriptors).
• Limiting Internet Exposure: Where external access is essential, restrict exposure by using VPNs, authenticated jump servers (e.g., Citrix, VDI), and strict source IP allowlisting.
• Transport Security: Implement and enforce HTTPS/TLS at all termination points, particularly where sensitive credentials are handled.
• General OT Hardening: Limit the number of internet-facing nodes, deploy anti-DDoS capabilities, and utilize application-aware firewalls that are capable of detecting and blocking malicious activity targeting common serialization/deserialization exploits.

These mitigations align with best practices for ICS/SCADA environments, as set out by both industry guidelines and CISA’s own Defense-in-Depth strategic documents.

Communication and Awareness​

Kaleris has proactively distributed security advisories to its customer base and made information available via public channels and official security contacts. CISA’s advisories reinforce the urgency by recommending that organizations review their current exposure, patch management strategies, remote access controls, and incident response playbooks.

Analysis: Notable Strengths and Gaps in Incident Response​

Strengths​

• Rapid Disclosure: Kaleris worked promptly with CISA to identify, document, and disclose the risk—avoiding the delays that sometimes plague vulnerabilities in proprietary ICS software.
• Clear Mitigation Pathways: Guidance is thorough, actionable, and tailored to enterprise environments, with interim and permanent remedial actions clearly explained.
• Industry Collaboration: Direct reporting to federal cybersecurity authorities reflects maturity in vendor transparency and incident response, signaling to customers that security is priority one.

Risks and Ongoing Challenges​

• Legacy System Drag: Maritime terminals often run legacy IT stacks due to the cost and operational disruption of upgrades. This inertia dramatically extends the risk window, increasing the likelihood of exploitation.
• Complex Ecosystem: Port environments feature a web of integrations with physical equipment vendors, customs platforms, and third-party application stacks. A vulnerability in N4 can cascade, opening up indirect attack vectors.
• Assumptions About Network Security: While segmentation is vital, real-world ports frequently struggle to maintain immaculate boundaries, especially during expansions or digital transformation projects. Attackers will exploit any lapse.
• Visibility Gaps: Without robust network monitoring and anomaly detection, attackers can quietly exploit serialization or data transmission misconfigurations.
• Downstream Implications: Compromise at the port level can propagate to carriers, forwarders, and national transportation energy grids due to the interconnectedness of logistics data flows.

Best Practices for Forward-Looking Security​

The Navis N4 episode offers several broad lessons for terminal operators, software vendors, and the ICS community:

• Regular Security Audits: ICS and OT software must undergo continual security review, including for serialization, transport protocols, and session management.
• Enforced Patch Discipline: Vendors and clients should formalize rapid patch evaluation and deployment processes, paired with robust regression testing to avoid operational impacts.
• Zero Trust Approaches: Shift from implicit trust in network boundaries to robust authentication, least-privilege enforcement, and continuous network traffic inspection.
• User Awareness and Training: Educate personnel (from gate clerks to system administrators) on the dangers of social engineering, phishing, and inadvertent data exposure.
• Vendor Collaboration: Foster trusted, open communication channels with software vendors and integrators—proactively monitor for new advisories and updates.

Conclusion: A Catalyst for Port Cybersecurity Modernization​

The open disclosure of severe vulnerabilities in a flagship TOS like Kaleris Navis N4 is a clarion call for all stakeholders in maritime and industrial supply chain operations. As port environments grow ever more digitized, the attack surface expands commensurately—demanding a new level of vigilance, investment, and cross-industry collaboration.
Kaleris’s prompt and transparent handling of the disclosure, paired with detailed mitigations and ongoing communication, sets a new bar for incident response. Yet the real work of hardening terminal operations is just beginning: rigorous software lifecycle management, continual network security assessment, and a culture of readiness are now non-negotiable across global critical infrastructure.
With billions in trade riding on the safe flow of cargo, port operators, IT teams, and government cybersecurity bodies must heed the lessons of the Navis N4 episode. Future operational resilience depends not just on innovative logistics, but on the relentless and coordinated defense of the digital foundations that keep trade—and the world—moving.

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Source: CISA Kaleris Navis N4 Terminal Operating System | CISA