CVE-2021-25369: Samsung Mobile Devices Improper Access Control Vulnerability

CVE-2021-25369 is an improper access control vulnerability in Samsung mobile devices that use the Mali GPU. It centers on the sec_log file and allows sensitive kernel information to become readable from userspace.

This matters to IT and security teams because the leaked kernel details can serve as a building block for further compromise. The flaw has been chained with CVE-2021-25337 and CVE-2021-25370, increasing the risk that a local foothold could escalate into broader device control. Ransomware use is not documented, yet any exposure of kernel state on managed mobile fleets warrants prompt attention.

How it works

The weakness is catalogued as CWE-200, exposure of sensitive information. On affected Samsung devices equipped with a Mali GPU, access controls around the sec_log file are insufficient. As a result, processes running in userspace can obtain kernel-level details that should remain restricted.

An attacker who already has code execution on the device—whether through a malicious app, another vulnerability, or physical access—can read the improperly protected sec_log content. The harvested kernel information supplies the reconnaissance needed to refine subsequent exploits. Public detail does not describe the precise read primitives or memory layouts involved; those mechanics must be confirmed against the vendor advisory. The documented chaining with two companion CVEs shows how the information leak can be combined with other flaws to achieve higher impact.

Am I affected? How to find it in your systems

The vulnerability applies to Samsung mobile devices that incorporate a Mali GPU. Typical environments include corporate-issued smartphones and tablets, BYOD devices enrolled in mobile-device management (MDM), and any Samsung handset used to access enterprise resources.

• Inventory all Samsung Android devices via your MDM console, asset-management database, or endpoint-detection platform; note model numbers and GPU type where available.
• Cross-reference each device’s security-patch level and firmware build against the Samsung advisory for CVE-2021-25369; exact affected versions are not listed here and must be verified with the vendor.
• Examine device logs and telemetry for anomalous reads of sec_log or related kernel interfaces. Unusual userspace access patterns to system logging facilities may indicate probing, though definitive indicators of compromise require confirmation against vendor guidance.
• Prioritize devices that process sensitive data, hold elevated privileges, or operate outside strict network controls.

How to remediate

The primary remediation is to apply the updates issued by Samsung, following the vendor’s instructions as directed by CISA. Confirm the precise patch packages, build numbers, and deployment steps in the official advisory before rolling them out.

• Push the security update through your MDM or enterprise mobility management solution, or instruct users to install it via the official Samsung update channel.
• After installation, verify that the device reports the corrected security-patch level.
• For the broader class of improper-access-control issues affecting kernel interfaces, enforce least-privilege app permissions, restrict sideloading, and keep the device’s SELinux or equivalent mandatory-access-control policy in enforcing mode.
• Retire or isolate any devices that can no longer receive updates.

If you can't patch immediately

When immediate patching is blocked by operational constraints, apply compensating controls that reduce the attack surface until the official update can be installed.

• Segment affected devices onto restricted network zones that limit lateral movement and access to high-value resources.
• Use MDM policies to disable unnecessary debugging interfaces, restrict app installation sources, and enforce strong authentication.
• Deploy virtual patching or behavioral monitoring rules on any mobile-threat-defense or endpoint-protection platform that can detect abnormal access to kernel logging facilities.
• Increase logging and alerting around process creation, privilege changes, and file-system access to sec_log or equivalent paths; investigate anomalies promptly.
• Where feasible, temporarily remove or quarantine high-risk applications that could serve as an initial vector for local code execution.

If your data may have been exposed

Actively exploited vulnerabilities can lead to device compromise and subsequent data exposure. Although ransomware use is not documented for this CVE, treat any confirmed exploitation as a potential breach event. Review device logs, revoke credentials stored on the device, and force re-authentication for enterprise services. Readers can also run a free exposure scan of their email address to check whether associated accounts appear in known breach data sets.