CVE-2025-26785: Samsung Exynos 1280 Buffer Overflow Flaw

CVE-2025-26785 Overview

CVE-2025-26785 is an out-of-bounds write vulnerability [CWE-787] in the Non-Access Stratum (NAS) component of multiple Samsung Exynos Mobile Processors, Wearable Processors, and Modems. The flaw stems from a missing length check during NAS message processing. A remote attacker can trigger memory corruption over the cellular network without authentication or user interaction. Samsung documented the issue across its Exynos 980, 990, 850, 1080, 2100, 1280, 2200, 1330, 1380, 1480, 2400, W920, W930, W1000, and Modem 5123, 5300, and 5400 product lines.

Critical Impact
Remote attackers can corrupt baseband memory through crafted NAS signaling, leading to modem crashes and denial of service on affected Samsung Exynos devices.

Affected Products

Samsung Exynos Mobile Processors: 980, 990, 850, 1080, 2100, 1280, 2200, 1330, 1380, 1480, 2400
Samsung Exynos Wearable Processors: W920, W930, W1000
Samsung Exynos Modems: 5123, 5300, 5400

Discovery Timeline

2025-05-14 - CVE-2025-26785 published to NVD
2025-06-25 - Last updated in NVD database

Technical Details for CVE-2025-26785

Vulnerability Analysis

The vulnerability resides in the NAS layer of the Samsung Exynos baseband firmware. NAS is the protocol used between user equipment and the mobile core network for mobility management, session management, and authentication signaling. The affected code path processes incoming NAS messages without first validating the declared length against the destination buffer size. When the parser copies attacker-controlled data, the write extends past the buffer boundary and corrupts adjacent memory regions within the modem.

Because NAS messages traverse the radio interface, an attacker positioned on the cellular network — for example, operating a rogue base station or a compromised network element — can deliver the malformed payload directly to the modem. No interaction is required from the device user, and no credentials are required on the device side. Successful exploitation primarily affects availability, causing the modem to crash or enter an unstable state.

Root Cause

The root cause is the absence of a bounds check on a length field within a NAS message handler. The baseband parser trusts an attacker-controlled length value when copying message contents into a fixed-size structure. This is a classic out-of-bounds write pattern catalogued under [CWE-787].

Attack Vector

Exploitation requires the attacker to send a crafted NAS message to a target device camped on a malicious or attacker-influenced cellular cell. The attack vector is network-based, requires low complexity, and does not require privileges or user interaction. The realized impact is high availability loss; confidentiality and integrity impacts are not asserted by Samsung's advisory.

No public proof-of-concept code has been released for CVE-2025-26785. Refer to the Samsung CVE-2025-26785 Details page for vendor-supplied technical context.

Detection Methods for CVE-2025-26785

Indicators of Compromise

Unexpected modem resets, baseband panics, or repeated cellular radio reinitialization events recorded in device logs.
Loss of cellular connectivity correlated with proximity to unknown or unauthorized base stations.
Crash dumps referencing NAS message handlers within Exynos modem firmware.

Detection Strategies

Monitor mobile device management (MDM) telemetry for anomalous modem crash counters and radio subsystem restarts on Exynos-based handsets and wearables.
Use cellular threat detection tooling to identify rogue base stations and abnormal NAS signaling sequences in the vicinity of corporate facilities.
Correlate device-side baseband logs with carrier-side signaling records to identify malformed NAS Protocol Data Units (PDUs).

Monitoring Recommendations

Track Samsung security bulletin advisories and validate that managed devices have received the latest baseband firmware update.
Inventory deployed devices by Exynos chipset family to scope exposure and prioritize patch rollout.
Alert on repeated device reboots, IMS deregistration events, or modem watchdog triggers that may indicate exploitation attempts.

How to Mitigate CVE-2025-26785

Immediate Actions Required

Apply the Samsung baseband firmware update referenced in the vendor advisory as soon as it is offered to the affected device model.
Identify all Exynos-based phones, wearables, and modem-equipped devices in the fleet and confirm their firmware build numbers.
Prioritize patching for high-risk users, executives, and devices operating in regions with elevated rogue base station activity.

Patch Information

Samsung has published mitigation details and patched firmware references on its product security update portal. Consult the Samsung Product Security Updates page and the dedicated Samsung CVE-2025-26785 Details advisory. Firmware delivery is handled by device OEMs and mobile carriers; ensure over-the-air updates are not blocked by enterprise policy.

Workarounds

Where patching is delayed, restrict use of affected devices in high-risk locations or environments where rogue cellular infrastructure is plausible.
Enforce MDM policies that require the latest available carrier-pushed firmware before granting access to corporate resources.
Disable 2G/legacy radio access technologies where supported, reducing the surface available to downgrade-based signaling attacks.

bash

# Example: query Android device build and baseband version for inventory
adb shell getprop ro.product.model
adb shell getprop gsm.version.baseband
adb shell getprop ro.build.version.security_patch