CVE-2021-25487: Samsung Mobile Devices Out-of-Bounds Read Vulnerability

CVE-2021-25487 is an out-of-bounds read vulnerability in the modem interface driver on Samsung mobile devices. It stems from missing boundary checks on a buffer inside set_skb_priv(), which can allow an attacker to trigger remote code execution by causing the system to dereference an invalid function pointer. For IT and security teams managing fleets of Samsung handsets or tablets, this matters because a successful exploit could give an attacker code execution on the device itself, potentially compromising corporate data, credentials, or network access if the device is enrolled in enterprise management.

Public detail is limited to the CISA description and the CWE classification; exact affected builds, attack vectors, and conditions must be confirmed against the vendor advisory before any assessment or response plan is finalized.

How it works

The weakness is classified as CWE-125 (Out-of-bounds Read). In the modem interface driver, the function set_skb_priv() fails to enforce proper boundary checking on a buffer. An attacker who can supply crafted input that reaches this code path can cause the driver to read past the end of the intended buffer. The CISA summary states that this leads to remote code execution through the subsequent dereference of an invalid function pointer. No further exploit mechanics, required privileges, or network versus local delivery details are provided in the available facts, so defenders should treat the issue as a remote-code-execution risk in the modem stack and verify the precise preconditions in Samsung’s advisory.

Am I affected? How to find it in your systems

The vulnerability affects Samsung mobile devices. These devices commonly appear as employee-owned or corporate-issued phones and tablets that may be enrolled in mobile-device management (MDM) platforms, connected to corporate Wi-Fi or VPN, or used for email and collaboration apps.

• Inventory all Samsung devices via your MDM console, asset-management database, or network discovery tools that report manufacturer and model.
• Record the exact software build, baseband/modem version, and security-patch level for each device; compare those values against the fixed versions listed in the vendor advisory.
• If devices are not centrally managed, require users to report Settings → About phone → Software information (or equivalent) so you can check the security patch date and baseband version.
• Look for anomalous modem-related crashes, unexpected reboots, or kernel logs that reference the modem interface driver; such telemetry may indicate attempted exploitation, though absence of these signs does not prove safety.

Because no specific version ranges are supplied in the facts, treat every Samsung mobile device as potentially affected until the advisory confirms otherwise.

How to remediate

The primary remediation is to apply the updates issued by Samsung according to the vendor instructions. CISA’s required action is to apply those updates or to discontinue use of the product if updates are unavailable. Once the vendor patch is installed, verify the new security-patch level or baseband version matches the fixed release.

• Push the update through MDM as soon as it is available for each model and carrier variant.
• For unmanaged devices, instruct users to install the update via Settings → Software update and confirm successful installation.
• After patching, re-inventory devices to ensure no residual vulnerable builds remain in the environment.
• As a general hardening step for this class of modem-driver flaws, keep devices on the latest supported OS branch and disable unused radio features where policy permits.

If you can't patch immediately

When immediate patching is not feasible, apply compensating controls that reduce exposure of the modem interface and limit the impact of a successful exploit.

• Segment devices that cannot be updated onto restricted network segments or guest Wi-Fi that has no access to sensitive corporate resources.
• Enforce MDM policies that disable unnecessary radios, Bluetooth, or USB debugging if those features are not required for business use.
• Monitor for indicators of compromise such as unexpected process crashes in modem-related components, anomalous network traffic originating from the device, or sudden enrollment of new certificates or VPN profiles.
• Consider temporary virtual-patching or traffic-filtering rules at the network edge that block known malicious patterns targeting mobile modem stacks, while recognizing that such rules are imperfect without vendor-specific signatures.
• If the risk cannot be reduced to an acceptable level, remove the device from corporate networks or replace it until a patch is available.

If your data may have been exposed

Actively exploited vulnerabilities of this type can lead to device compromise and subsequent data exposure. Known ransomware use of CVE-2021-25487 is not documented in the available facts. If you suspect a device was compromised, isolate it, collect forensic artifacts, and rotate any credentials or tokens that may have been accessible from the device. You can also run a free exposure scan of your email addresses to check whether those addresses appear in known breach data sets.