CVE-2025-27807: Samsung Exynos Buffer Overflow Vulnerability

CVE-2025-27807 Overview

CVE-2025-27807 is a critical out-of-bounds write vulnerability affecting a wide range of Samsung Exynos mobile processors, wearable processors, and modems. The vulnerability stems from insufficient length validation when processing Non-Access Stratum (NAS) packets, allowing remote attackers to write beyond allocated memory boundaries. This flaw could enable attackers to corrupt memory, potentially leading to code execution or denial of service on affected devices.

Critical Impact

Remote attackers can exploit this vulnerability over the network without authentication to cause out-of-bounds memory writes, potentially compromising device integrity and availability.

Affected Products

• Samsung Exynos Mobile Processors: 980, 990, 850, 1080, 2100, 1280, 2200, 1330, 1380, 1480, 2400, 1580
• Samsung Exynos Wearable Processors: 9110, W920, W930, W1000
• Samsung Exynos Modems: 5123, 5300, 5400

Discovery Timeline

• 2026-01-05 - CVE-2025-27807 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-27807

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), a memory corruption flaw that occurs when software writes data past the boundaries of allocated memory buffers. In the context of Samsung Exynos processors and modems, the vulnerability exists in the handling of NAS (Non-Access Stratum) packets, which are used for signaling between mobile devices and the cellular network core.

The root issue lies in the baseband processor's failure to properly validate the length field of incoming NAS messages before processing them. When a malformed NAS packet with an invalid or manipulated length value is received, the processor attempts to write packet data into memory without verifying that the destination buffer can accommodate the specified length, resulting in memory corruption beyond the intended bounds.

Root Cause

The vulnerability originates from missing boundary checks in the NAS packet processing routines within the Exynos baseband firmware. NAS protocol messages contain length fields that indicate the size of subsequent data elements. The affected Exynos processors trust these length values without proper validation, allowing attackers to specify arbitrary lengths that exceed buffer allocations. This lack of input validation is a common source of memory safety issues in low-level firmware implementations.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no user interaction or authentication. An attacker can exploit this flaw by sending specially crafted NAS packets to a target device over the cellular network. The malformed packets trigger the out-of-bounds write condition in the baseband processor's memory space. Given that baseband processors operate with high privileges and handle sensitive telecommunications functions, successful exploitation could have severe consequences including:

• Memory corruption leading to device instability or crashes
• Potential execution of arbitrary code in the baseband context
• Denial of service affecting cellular connectivity
• Possible escalation to compromise other device components

The vulnerability affects both mobile and wearable devices using the listed Exynos chipsets, significantly expanding the attack surface across Samsung's device ecosystem.

Detection Methods for CVE-2025-27807

Indicators of Compromise

• Unexpected device crashes or reboots, particularly during cellular network operations
• Abnormal baseband processor behavior or modem connectivity issues
• Unusual memory consumption patterns in system diagnostics
• Device instability when connected to unfamiliar cellular networks

Detection Strategies

• Monitor system logs for baseband processor crashes or exceptions that may indicate exploitation attempts
• Implement network-level monitoring at cellular infrastructure to identify anomalous NAS packet patterns
• Deploy endpoint detection solutions capable of monitoring baseband and modem activity
• Establish baseline device behavior to detect deviations that may signal compromise

Monitoring Recommendations

• Enable comprehensive logging on mobile device management (MDM) platforms to track device health metrics
• Implement cellular network security monitoring where infrastructure access permits
• Monitor for indicators of baseband firmware tampering or unauthorized modifications
• Conduct regular security assessments of mobile fleet devices using vulnerable chipsets

How to Mitigate CVE-2025-27807

Immediate Actions Required

• Check device firmware versions against Samsung's security advisory to determine vulnerability status
• Apply the latest security patches from Samsung as soon as they become available
• Consider restricting devices with vulnerable chipsets from connecting to untrusted cellular networks
• Prioritize patching for devices handling sensitive information or critical operations

Patch Information

Samsung has acknowledged this vulnerability and published security update information. Organizations and users should refer to the Samsung Security Updates portal for the latest patch availability. Detailed information specific to this vulnerability is available at the Samsung CVE-2025-27807 Update page. Apply firmware updates through official Samsung channels to ensure device protection.

Workarounds

• Until patches are applied, avoid connecting vulnerable devices to untrusted or public cellular networks where possible
• Consider using Wi-Fi connectivity as an alternative when cellular network exposure is a concern
• Implement mobile device management policies to enforce firmware update compliance
• Maintain device inventory to track which devices require patching for this vulnerability

For enterprise environments, coordinate with mobile carriers and Samsung support to understand patch deployment timelines and interim risk mitigation options for affected device fleets.