CVE-2021-25370

What it actually does

This vulnerability is a local kernel-level memory corruption issue in the Samsung Display Processing Unit (DPU) driver used on affected Android devices before the SMR Mar-2021 Release 1 security update. The flaw stems from incorrect handling of a file descriptor, which can lead to use-after-free-style memory corruption in kernel context. The documented impact is availability loss: a sufficiently privileged local attacker can trigger a kernel panic and crash the device. The CVSS vector indicates local access, low attack complexity, high privileges required, no user interaction, and high availability impact, with no direct confidentiality or integrity impact described.

Why it matters to the business

Successful exploitation can cause affected Android devices to crash or become unstable, disrupting mobile workforce operations, device availability, field services, point-of-sale use cases, or any business process that depends on managed Android devices. Because this vulnerability is listed in CISA KEV and has observed exploitation in the wild, organizations should treat unpatched affected devices as higher priority even though the CVSS score is moderate and EPSS is currently low and flat. The CISA KEV remediation deadline was 2022-11-29, so any still-exposed devices are materially overdue for patching.

How an attack unfolds

An attacker first needs local access with high privileges on an affected Android device, such as through a malicious app that has already gained elevated privileges, a chained exploit, physical access with device control, or prior compromise. The attacker then interacts with the vulnerable DPU driver interface and supplies or manipulates a file descriptor in a way the driver handles incorrectly. This causes memory corruption in kernel space. In the known documented impact, the corruption results in a kernel panic, forcing the device to crash or reboot. In real-world exploitation, this type of local kernel bug may be used as part of a broader exploit chain, but the provided impact for this CVE is denial of service rather than data theft or privilege escalation.

How to fix it

Update affected Android/Samsung mobile devices to the vendor security maintenance release SMR Mar-2021 Release 1 or later, or to the latest available Android security update supplied by the device manufacturer or carrier. Because no exact package-level fixed versions were provided, use device model, Android security patch level, and vendor bulletin status to confirm remediation. For managed fleets, enforce minimum Android security patch levels through MDM/UEM compliance policies, block or quarantine devices below the required patch level, and prioritize devices that are shared, kiosk-mode, field-deployed, or exposed to untrusted app installation. If immediate patching is not possible, reduce risk by restricting sideloading, limiting high-privilege app installation, enforcing Play Protect or equivalent mobile threat defense controls, and removing devices from sensitive workflows until updated.

How to confirm the fix worked

Confirm the device reports an Android security patch level at or after the vendor release that includes SMR Mar-2021 Release 1, or a later cumulative security update for the affected device model. Validate through MDM/UEM inventory, device settings, OEM update status, or Android Enterprise reporting. Where possible, compare device model and build number against the OEM security bulletin. Confirm that vulnerable pre-March-2021 Samsung firmware builds are no longer present in the fleet. For exposure detection, identify Android devices with outdated security patch levels, Samsung builds released before the March 2021 maintenance release, or devices no longer receiving OEM security updates.

Typical attack path

1. Obtain local execution on an affected Android device.
2. Acquire or already possess high privileges required to interact with the vulnerable driver path.
3. Access the Samsung DPU driver interface exposed on the device.
4. Trigger the incorrect file descriptor handling condition.
5. Cause kernel memory corruption in the DPU driver.
6. Induce a kernel panic, resulting in device crash, reboot, or operational interruption.

How to detect it

To determine whether exploitation may have already occurred, review mobile device management telemetry, Android bug reports, kernel crash logs, pstore/ramoops data, logcat captures, OEM diagnostic logs, and mobile threat defense alerts. Look for repeated unexpected reboots, kernel panics, or crash reports referencing the DPU/display driver shortly after suspicious local activity, privileged app execution, sideloaded APK installation, rooting activity, or exploitation alerts. Useful artifacts include Android bugreport archives, /sys/fs/pstore contents, /proc/last_kmsg where available, tombstones, kernel logs, and MDM records of abnormal device restarts. Because the known impact is denial of service and the vulnerability is local, absence of network indicators does not rule out exploitation. Correlate crash timing with newly installed apps, privilege escalation detections, rooting/jailbreak indicators, ADB activity, and noncompliant security patch levels.

• dpu
• DPU
• kernel panic
• Kernel panic
• /sys/fs/pstore/console-ramoops
• /sys/fs/pstore/console-ramoops-0
• /proc/last_kmsg
• /data/tombstones/
• last_kmsg
• ramoops
• unexpected reboot
• device rebooted
• display driver
• file descriptor

What your security team should do

• Immediately inventory Android/Samsung devices and identify any with security patch levels older than the March 2021 vendor security maintenance release.
• Prioritize remediation for managed, shared, kiosk, executive, privileged-user, field-service, and production-use mobile devices.
• Enforce MDM/UEM compliance rules requiring current Android security patch levels and block noncompliant devices from corporate resources.
• Review mobile threat defense alerts and device crash telemetry for repeated kernel panic or DPU-related crash artifacts.
• Restrict sideloading and remove unnecessary high-privilege applications on devices that cannot be updated immediately.
• Retire or isolate devices that are end-of-life and cannot receive the vendor security update.
• Because the vulnerability is in CISA KEV and known exploited, treat remaining exposure as an overdue remediation item regardless of the low current EPSS value.