CVE-2025-54329: Samsung Exynos Buffer Overflow Flaw

CVE-2025-54329 Overview

A heap overflow vulnerability has been discovered in the Non-Access Stratum (NAS) component of multiple Samsung Exynos mobile processors, wearable processors, and modems. The vulnerability exists in the function responsible for sending multiple-payload messages, including SMS messages. Due to missing bounds checking when processing these messages, an attacker can trigger a heap-based buffer overflow condition, potentially leading to denial of service.

Critical Impact

This vulnerability affects a wide range of Samsung Exynos processors used in smartphones, wearables, and cellular modems, potentially impacting millions of devices worldwide. Successful exploitation could result in device crashes or service disruption via malicious network traffic.

Affected Products

• Samsung Exynos Mobile Processors (980, 990, 850, 2100, 1280, 2200, 1330, 1380, 1480, 2400, 1580, 2500)
• Samsung Exynos Wearable Processors (W920, W930, W1000)
• Samsung Exynos Modems (5123, 5300, 5400)

Discovery Timeline

• 2025-11-04 - CVE-2025-54329 published to NVD
• 2025-11-07 - Last updated in NVD database

Technical Details for CVE-2025-54329

Vulnerability Analysis

This vulnerability is classified as CWE-122 (Heap-based Buffer Overflow). The flaw resides within the NAS (Non-Access Stratum) layer, which handles signaling between the mobile device and the cellular network core. The vulnerable function processes multiple-payload messages, such as SMS, without performing adequate bounds validation on the incoming data. When an attacker sends a specially crafted message with oversized or malformed payloads, the function writes beyond the allocated heap buffer, corrupting adjacent memory structures.

The network-based attack vector means exploitation can occur remotely without requiring any user interaction or authentication. The primary impact is availability, as heap corruption in the baseband processor can cause device instability, modem crashes, or complete loss of cellular connectivity.

Root Cause

The root cause is the absence of proper bounds checking in the NAS message handling function. When processing concatenated or multi-part messages (including SMS), the code fails to validate that the total payload size fits within the allocated heap buffer before copying data. This oversight allows attackers to supply oversized message payloads that exceed buffer boundaries.

Attack Vector

The vulnerability can be exploited remotely over the cellular network. An attacker could craft malicious NAS messages containing multiple payloads that exceed expected size limits. When the target device's baseband processor receives and processes these messages, the heap overflow occurs. Since this vulnerability is in the modem firmware, exploitation happens at the baseband level, potentially bypassing application-layer security controls.

The attack does not require physical access to the device, user interaction, or prior authentication. Exploitation targets the cellular modem's message processing directly through the mobile network.

Detection Methods for CVE-2025-54329

Indicators of Compromise

• Unexpected device reboots or modem crashes, particularly when receiving SMS or cellular signaling messages
• Cellular connectivity failures or intermittent loss of network registration
• Abnormal baseband processor behavior or error logs indicating memory corruption
• Repeated modem subsystem restarts visible in device diagnostic logs

Detection Strategies

• Monitor device logs for baseband processor crashes or NAS-related errors
• Implement network-level monitoring for anomalous NAS message patterns or oversized payloads
• Deploy endpoint detection solutions capable of monitoring modem subsystem health
• Correlate cellular network events with device stability issues across managed device fleets

Monitoring Recommendations

• Enable verbose logging on mobile device management (MDM) platforms to capture modem crash events
• Work with carriers to identify potential exploitation attempts at the network level
• Monitor Samsung's security advisories for firmware update availability
• Track affected device populations using asset inventory correlated with the vulnerable processor list

How to Mitigate CVE-2025-54329

Immediate Actions Required

• Check Samsung's Product Security Updates page for firmware patches
• Apply the latest firmware updates to all devices containing affected Exynos processors
• Prioritize patching for devices with high exposure or sensitive data
• Review the CVE-2025-54329 advisory for specific remediation guidance

Patch Information

Samsung has published security advisories addressing this vulnerability. Organizations should obtain firmware updates through their device vendors or directly from Samsung Semiconductor's security portal. The patches add proper bounds validation to the NAS message processing function to prevent heap overflow conditions.

For enterprise deployments, coordinate firmware updates through your MDM solution to ensure consistent patch deployment across affected devices. Consumer devices should receive updates through standard over-the-air (OTA) update mechanisms from device manufacturers.

Workarounds

• No direct workarounds are available for this baseband-level vulnerability
• Limit exposure by avoiding use of affected devices in high-risk environments until patched
• Consider network segmentation or enhanced monitoring for critical assets using vulnerable devices
• Contact Samsung or device manufacturers for emergency patch availability if immediate remediation is required

# Check device firmware version (Android)
adb shell getprop ro.build.display.id
adb shell getprop gsm.version.baseband

# Review modem crash logs
adb logcat -b radio | grep -i "crash\|error\|nas"