CVE-2025-59440 Overview
A Denial of Service vulnerability has been identified in the USIM (Universal Subscriber Identity Module) component across a wide range of Samsung Exynos processors, wearable processors, and modems. The vulnerability stems from improper handling of SIM card proactive commands, which can be exploited to cause a denial of service condition on affected devices.
This vulnerability affects the baseband firmware responsible for processing SIM Toolkit (STK) proactive commands, which are instructions sent from the SIM card to the mobile device to perform specific actions. When malformed or specially crafted proactive commands are processed, the USIM handler fails to properly validate or handle the input, resulting in service disruption.
Critical Impact
Attackers can exploit this vulnerability remotely over the network to cause denial of service on Samsung devices using affected Exynos processors and modems, potentially disrupting cellular connectivity and device functionality.
Affected Products
- Samsung Exynos Mobile Processors (980, 990, 850, 1080, 2100, 1280, 2200, 1330, 1380, 1480, 2400, 1580, 2500)
- Samsung Exynos Wearable Processors (9110, W920, W930, W1000)
- Samsung Exynos Modems (5123, 5300, 5400)
Discovery Timeline
- April 6, 2026 - CVE-2025-59440 published to NVD
- April 7, 2026 - Last updated in NVD database
Technical Details for CVE-2025-59440
Vulnerability Analysis
The vulnerability exists within the USIM component of Samsung Exynos baseband firmware. The USIM interface processes SIM Toolkit (STK) proactive commands, which are part of the GSM/3GPP specification allowing SIM cards to initiate actions on the mobile device. These commands include operations such as displaying text, sending SMS, launching browsers, and managing calls.
The root issue lies in how the baseband firmware handles these proactive commands. When processing certain command sequences or malformed command structures, the USIM handler does not adequately validate input parameters before processing, leading to resource exhaustion or an unhandled exception state that causes the baseband to become unresponsive.
The attack can be initiated remotely over the network, requires no user interaction, and does not require authentication. This makes the vulnerability particularly concerning for enterprise environments where device availability is critical.
Root Cause
The vulnerability is classified as CWE-400 (Uncontrolled Resource Consumption). The baseband firmware's USIM component fails to implement proper bounds checking and resource management when processing SIM card proactive commands. This allows an attacker to trigger excessive resource consumption or cause the command processing logic to enter a failure state, resulting in denial of service.
The improper handling occurs at the firmware level within the modem subsystem, which operates independently from the main application processor. This isolation means that while the cellular functionality is disrupted, the device's main operating system may continue to function, though without network connectivity.
Attack Vector
The attack can be executed remotely over the cellular network. An attacker with the capability to send specially crafted signaling messages or through a malicious SIM card could trigger the vulnerability. The network-based attack vector is particularly concerning as it does not require physical access to the target device.
Potential attack scenarios include:
- Rogue Base Station Attack: An attacker operating a malicious base station could send crafted proactive commands to devices within range
- Malicious SIM Card: A compromised or specially programmed SIM card could issue malformed proactive commands to trigger the vulnerability
- Network-Level Attack: Exploitation through cellular network signaling if an attacker has access to core network infrastructure
The vulnerability does not affect data confidentiality or integrity but has a high impact on system availability.
Detection Methods for CVE-2025-59440
Indicators of Compromise
- Unexpected baseband crashes or modem restarts on Samsung devices with Exynos processors
- Repeated loss of cellular connectivity without apparent cause
- Device logs showing USIM-related errors or proactive command processing failures
- Abnormal patterns in modem diagnostic logs related to STK command handling
Detection Strategies
- Monitor device telemetry for unusual baseband restart patterns across fleet devices
- Implement logging and alerting for USIM subsystem errors at the MDM (Mobile Device Management) level
- Track cellular connectivity disruptions and correlate across multiple devices to identify potential targeted attacks
- Review modem crash dumps for patterns consistent with proactive command handling failures
Monitoring Recommendations
- Enable enhanced logging on Samsung devices where available to capture baseband events
- Deploy network-level monitoring to detect unusual signaling patterns that may indicate attack attempts
- Establish baseline metrics for normal device connectivity to identify anomalies
- Coordinate with mobile network operators to monitor for suspicious activity targeting Samsung devices
How to Mitigate CVE-2025-59440
Immediate Actions Required
- Review the Samsung CVE-2025-59440 Advisory for specific patch information
- Prioritize firmware updates for devices using affected Exynos processors and modems
- Implement device management policies to ensure timely security updates are applied
- Consider network segmentation and enhanced monitoring for critical devices until patches are deployed
Patch Information
Samsung has published security guidance for this vulnerability. Organizations should consult the Samsung Product Security Updates page for the latest firmware updates addressing CVE-2025-59440.
Firmware updates for Exynos processors are typically distributed through:
- Device OTA (Over-The-Air) updates from device manufacturers (e.g., Samsung mobile devices)
- Enterprise MDM solutions for managed device deployments
- Carrier-specific update channels
The specific patch availability depends on the device manufacturer and carrier, as Exynos processors are used across multiple Samsung device lines and in some third-party devices.
Workarounds
- No complete workarounds are available as the vulnerability exists at the baseband firmware level
- Limit exposure by avoiding untrusted network environments until patches are applied
- For high-security environments, consider using devices with non-affected chipsets until remediation is complete
- Monitor Samsung's security advisories for updates on mitigation strategies
# Verify device firmware version on Samsung Android devices
# Settings > About Phone > Software Information > Baseband version
# Compare against Samsung's security bulletin to confirm patch status
adb shell getprop gsm.version.baseband
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
