CVE-2025-67841: Nordic nRF54H20 Complexity Vulnerability

CVE-2025-67841 Overview

CVE-2025-67841 is an algorithmic complexity vulnerability affecting Nordic Semiconductor IronSide SE for nRF54H20 devices running firmware versions prior to 23.0.2+17. This vulnerability (CWE-407: Inefficient Algorithmic Complexity) allows remote attackers to trigger resource exhaustion conditions through specially crafted inputs, potentially causing denial of service on affected embedded devices.

Critical Impact

Remote attackers can exploit algorithmic inefficiencies to exhaust device resources, causing denial of service conditions on Nordic Semiconductor nRF54H20-based IoT and embedded systems without requiring authentication.

Affected Products

• Nordic Semiconductor IronSide SE for nRF54H20 versions before 23.0.2+17
• Embedded devices and IoT systems utilizing the nRF54H20 platform with vulnerable firmware
• Applications relying on IronSide SE secure element functionality

Discovery Timeline

• 2026-04-15 - CVE-2025-67841 published to NVD
• 2026-04-16 - Last updated in NVD database

Technical Details for CVE-2025-67841

Vulnerability Analysis

This vulnerability stems from inefficient algorithmic complexity (CWE-407) within the Nordic Semiconductor IronSide SE secure element implementation for the nRF54H20 platform. The flaw enables attackers to submit inputs that trigger worst-case computational complexity, leading to excessive resource consumption and potential denial of service.

The network-accessible nature of this vulnerability allows remote exploitation without requiring authentication or user interaction. When exploited, the vulnerable algorithm consumes disproportionate computational resources relative to the input size, effectively starving legitimate operations of processing time and memory.

Root Cause

The root cause is an algorithmic complexity issue where certain input patterns cause the affected component to exhibit worst-case time or space complexity. This type of vulnerability typically occurs when algorithms with polynomial or exponential worst-case complexity are exposed to untrusted input without proper bounds checking or complexity limiting mechanisms.

In embedded systems like the nRF54H20, such resource exhaustion can be particularly impactful due to constrained processing power and memory resources. The IronSide SE secure element, designed to provide hardware security features, becomes a vector for denial of service when processing adversarially crafted inputs.

Attack Vector

The vulnerability is exploitable over the network with low attack complexity. An attacker does not require privileges or user interaction to exploit this flaw. The attack targets system availability by causing resource exhaustion through algorithmic inefficiency.

An attacker can craft specific input patterns that maximize computational overhead within the vulnerable algorithm. When processed by the IronSide SE component, these inputs cause the system to enter computationally expensive operations, potentially rendering the device unresponsive or significantly degraded.

For detailed technical information about the vulnerability mechanism, refer to the Nordic Semiconductor Security Advisory.

Detection Methods for CVE-2025-67841

Indicators of Compromise

• Unusual CPU utilization spikes on nRF54H20-based devices without corresponding legitimate workload
• Device unresponsiveness or delayed responses to normal operational requests
• Memory exhaustion warnings or errors in device logs
• Network traffic patterns showing repeated requests to IronSide SE interfaces

Detection Strategies

• Monitor embedded device resource utilization for anomalous patterns indicating algorithmic complexity attacks
• Implement network traffic analysis to detect potential exploitation attempts targeting affected devices
• Deploy SentinelOne Singularity for IoT to monitor embedded device behavior and detect denial of service conditions
• Establish baseline performance metrics for nRF54H20 devices to identify deviations indicative of exploitation

Monitoring Recommendations

• Enable verbose logging on affected devices to capture input patterns and resource utilization metrics
• Implement rate limiting on network interfaces to mitigate flood-based exploitation attempts
• Configure alerts for device watchdog resets or timeout conditions that may indicate successful exploitation
• Monitor fleet-wide device health to identify targeted attacks against specific device populations

How to Mitigate CVE-2025-67841

Immediate Actions Required

• Upgrade Nordic Semiconductor IronSide SE firmware to version 23.0.2+17 or later on all affected nRF54H20 devices
• Audit device inventory to identify all deployments running vulnerable firmware versions
• Implement network segmentation to limit exposure of affected devices to untrusted networks
• Apply rate limiting controls at network boundaries to reduce exploitation risk during patch rollout

Patch Information

Nordic Semiconductor has addressed this vulnerability in IronSide SE version 23.0.2+17 and later. Organizations should consult the Nordic Semiconductor Security Advisory (SA-2025-447) for detailed patch information and firmware update procedures.

For devices deployed in field environments, coordinate firmware updates through established device management channels. Verify firmware integrity after updates using cryptographic verification mechanisms provided by the Nordic Semiconductor toolchain.

Workarounds

• Implement network access controls to restrict which systems can communicate with affected devices
• Deploy application-layer firewalls or proxies that can inspect and rate-limit requests to vulnerable interfaces
• Consider temporary isolation of affected devices from untrusted network segments until patches can be applied
• Enable hardware watchdog timers to automatically recover devices that become unresponsive due to exploitation attempts

# Example network isolation configuration for affected devices
# Restrict access to nRF54H20 devices to trusted management networks only

# iptables example - allow only trusted management subnet
iptables -A INPUT -s 10.0.100.0/24 -d <device_ip> -j ACCEPT
iptables -A INPUT -d <device_ip> -j DROP

# Verify firmware version on connected devices
nrfjprog --readcode --verify