CVE-2021-25371: Samsung Mobile Devices Unspecified Vulnerability

CVE-2021-25371 is an unspecified vulnerability in the DSP driver on Samsung mobile devices. It allows attackers to load ELF libraries inside the DSP. This matters because the DSP is a privileged component that handles media and signal processing; abuse can give an attacker a foothold on the device for further compromise of user data or device integrity. Confirm all product and version details against the vendor advisory.

CISA lists the required action as applying updates per vendor instructions or discontinuing use of the product if updates are unavailable. Known ransomware use is not documented for this CVE.

How it works

The weakness is classified as CWE-912 (Hidden Functionality). In this case the CISA summary states that the vulnerability resides within the DSP driver and permits attackers to load ELF libraries inside the DSP. On mobile platforms the DSP typically runs with elevated privileges separate from the main application processor. Loading arbitrary ELF libraries into that environment can let an attacker execute code outside normal application sandboxing and security checks.

Exact exploit mechanics, required privileges, and attack vectors are not detailed in the public summary. Defenders should treat this as a local or remote code-execution style issue in a privileged driver and verify the precise conditions in Samsung’s advisory. Do not assume network reachability or user interaction requirements without confirmation from the vendor.

Am I affected? How to find it in your systems

This issue affects Samsung mobile devices that include the vulnerable DSP driver. Such devices are commonly issued as corporate phones, BYOD endpoints, or test/development handsets. Inventory every Samsung device under management—phones, tablets, and any other Samsung mobile hardware that runs the vendor’s Android-based OS.

• Query MDM/EMM or inventory systems for manufacturer = Samsung and collect model numbers and OS build versions.
• Compare collected builds against the fixed versions listed in Samsung’s security bulletin for CVE-2021-25371; specifics must be confirmed against the vendor advisory.
• On devices that allow it, inspect kernel or DSP-related modules and driver versions via diagnostic tools or ADB (where policy permits).
• Review device logs and MDM telemetry for unexpected DSP crashes, library load failures, or anomalous process behavior originating from media or signal-processing components. Absence of such logs does not prove safety; many DSP operations leave limited user-visible traces.

If the device is no longer supported by Samsung, treat it as unpatchable and plan for replacement.

How to remediate

Patch first. Apply the security update provided by Samsung that addresses CVE-2021-25371, following the vendor’s instructions exactly. CISA’s required action is to apply updates per vendor instructions or discontinue use of the product if updates are unavailable.

• Push the update through your MDM/EMM as soon as it is available for each model and carrier variant.
• Verify successful installation by checking the security patch level or build number against the advisory.
• After patching, re-inventory devices to confirm no residual vulnerable builds remain.
• For devices that cannot receive the update, retire them from production use.

As general hardening for this class of driver issues, keep devices on supported OS versions, restrict sideloading of untrusted apps, and enforce strong device encryption and screen-lock policies so that any residual local access is harder to abuse.

If you can't patch immediately

Until the vendor update can be applied, reduce exposure with compensating controls:

• Segment affected devices onto restricted network segments or guest Wi-Fi with limited access to corporate resources.
• Disable or restrict features that heavily exercise the DSP (camera, voice assistants, media codecs) if business needs allow.
• Enforce application allow-listing and block installation of untrusted APKs that could serve as a delivery vector for local exploitation.
• Increase monitoring of device telemetry for DSP-related anomalies, unexpected reboots, or privilege-escalation indicators; feed alerts into your SIEM or EDR console.
• If a web or network path to the device exists, consider virtual patching or WAF rules that block known malicious payloads targeting mobile DSP interfaces, while recognizing that such rules are imperfect for local driver flaws.

These measures lower risk but do not eliminate it; schedule the official patch as the primary remediation.

If your data may have been exposed

Actively exploited vulnerabilities can lead to device compromise and subsequent data exposure. If you suspect devices were targeted before patching, treat them as potentially compromised: isolate them, collect forensic images where feasible, and rotate credentials that may have been stored or used on the device. Review access logs for anomalous activity originating from those handsets. As a quick additional check, you can run a free exposure scan of your email addresses to see whether they appear in known breach data sets.