CVE-2021-25372

What it actually does

CVE-2021-25372 is an improper boundary check in the Samsung DSP driver affecting Android devices using certain Samsung Exynos chipsets. A local attacker with high privileges can trigger out-of-bounds memory access in the driver, potentially allowing corruption or disclosure of memory in a privileged execution context. Because the vulnerable code is in a low-level device driver, successful exploitation can affect confidentiality, integrity, and availability of the device, including crashes, privilege abuse, or manipulation of sensitive memory.

Why it matters to the business

Successful exploitation can give an attacker deeper control over affected mobile devices that are already partially compromised, enabling theft of sensitive data, persistence, device instability, or bypass of security controls. The vulnerability is listed in CISA KEV and has been observed exploited in the wild, with a federal remediation due date of 2023-07-20, so organizations with fleets of affected Samsung Android devices should treat remediation as overdue even though the EPSS score is low and stable.

How an attack unfolds

An attacker typically first needs local code execution with high privileges on an affected Samsung Android device, such as through a malicious privileged application, chained exploit, or prior compromise. The attacker then interacts with the vulnerable Samsung DSP driver and supplies crafted input that fails the driver’s boundary validation. This causes out-of-bounds memory access in the driver context. Depending on memory layout, device model, firmware build, and exploit reliability, the attacker may use the memory corruption to disclose sensitive memory, tamper with kernel or driver data structures, destabilize the device, or strengthen an existing compromise. This flaw is not normally a stand-alone remote entry point; it is more likely to be used as part of a local exploit chain against Samsung Exynos-based Android devices.

How to fix it

Update affected Samsung Android devices to firmware containing Samsung SMR Mar-2021 Release 1 or later. If exact device-specific fixed builds are not centrally listed, verify through the device OEM security patch level and carrier/manufacturer firmware release notes that the March 2021 Samsung security maintenance release, or a later cumulative update, is installed. Prioritize affected products and platforms including Android devices using Samsung Exynos 2100, Exynos 980, and Exynos 9830 chipsets. Where immediate patching is not possible, reduce risk by restricting installation of untrusted applications, enforcing mobile device management controls, disabling developer options and sideloading where feasible, removing unsupported devices from sensitive access, and monitoring for signs of local privilege exploitation or abnormal driver interaction.

How to confirm the fix worked

Confirm that affected Samsung devices report a security patch level at or after the Samsung SMR Mar-2021 Release 1 update and that the vendor firmware build includes the March 2021 or later Samsung security maintenance release. Validate through mobile device management inventory, OEM firmware metadata, Android security patch level, carrier update status, and vulnerability scanner coverage where available. Devices that cannot receive the March 2021 or later Samsung security update should be considered exposed and should be replaced, isolated from sensitive applications, or restricted through compensating controls.

Typical attack path

1. Gain local execution on an affected Samsung Android device, often through malware, a chained vulnerability, or compromise of a privileged process.
2. Confirm the device uses an affected Samsung Exynos platform and is running firmware prior to Samsung SMR Mar-2021 Release 1.
3. Access the Samsung DSP driver interface from a sufficiently privileged context.
4. Send crafted input that abuses the improper boundary check and triggers out-of-bounds memory access.
5. Use the resulting memory access to read sensitive data, corrupt privileged memory, crash the device, or support further privilege and persistence objectives.
6. Clean up temporary artifacts where possible and continue operating under the elevated or more durable compromise.

How to detect it

Detection should focus on evidence of prior local exploitation rather than network indicators, because this is a local driver memory-corruption issue. Review Android logcat, kernel dmesg logs, tombstones, crash reports, mobile EDR telemetry, MDM compliance data, and application installation history from affected Samsung Exynos devices. Look for unexpected crashes or kernel panics involving the DSP driver, repeated access to DSP-related device nodes by nonstandard or recently installed privileged applications, SELinux audit messages involving DSP device access, signs of rooting or privilege escalation, abnormal native binaries executed from application-private directories, and device security patch levels older than Samsung SMR Mar-2021 Release 1. Because public, universal IOCs are limited, absence of these artifacts does not prove non-exploitation; correlate with device patch state, suspicious app provenance, privilege changes, and other exploit-chain indicators. For targeted-risk populations, preserve full device forensic images where possible before wiping or upgrading.

• Samsung security patch level earlier than SMR Mar-2021 Release 1
• Android security patch level earlier than 2021-03-01 on affected Samsung Exynos devices
• dmesg entries containing "dsp" near "panic"
• dmesg entries containing "dsp" near "oops"
• logcat entries containing "SELinux" and "dsp"
• logcat entries containing "avc: denied" and "dsp"
• tombstone crash reports referencing "dsp"
• unexpected access to DSP-related character devices by third-party or recently installed privileged applications

What your security team should do

• Inventory Samsung Android devices and identify models using Exynos 2100, Exynos 980, or Exynos 9830 chipsets.
• Prioritize remediation because the vulnerability is in CISA KEV, has active in-the-wild exploitation, and the KEV remediation deadline has passed.
• Require Samsung SMR Mar-2021 Release 1 or later firmware before allowing affected devices to access sensitive enterprise resources.
• Block or tightly control sideloading, unknown-source application installation, developer mode, and unmanaged privileged applications on affected Android devices.
• Use mobile threat defense, EDR, or MDM telemetry to look for rooted devices, unusual privileged app behavior, kernel crashes, and suspicious access to DSP-related device drivers.
• Quarantine or replace devices that are no longer receiving Samsung security maintenance releases.
• Review high-risk mobile users for targeted exploitation activity if affected devices were used before remediation.