CVE-2026-10420 Overview
CVE-2026-10420 is an untrusted pointer dereference vulnerability [CWE-822] in Samsung Open Source mTower, a trusted execution environment (TEE) implementation designed for microcontroller-based IoT devices. The flaw allows a local attacker to manipulate a pointer that is dereferenced without proper validation, leading to an availability impact on the affected device. Exploitation requires local access and user interaction. The vulnerability affects all mTower revisions prior to commit 102d3dc75cf8e58e68e4bea54ae3c803992c91be.
Critical Impact
Successful exploitation of CVE-2026-10420 can crash the mTower trusted execution environment, disrupting the security guarantees the TEE provides to IoT device firmware and applications.
Affected Products
- Samsung Open Source mTower (all builds before commit 102d3dc75cf8e58e68e4bea54ae3c803992c91be)
- IoT firmware and applications relying on mTower for trusted execution
- Downstream projects integrating vulnerable mTower revisions
Discovery Timeline
- 2026-09-01 - CVE-2026-10420 published to NVD
- 2026-09-01 - Last updated in NVD database
Technical Details for CVE-2026-10420
Vulnerability Analysis
The vulnerability is classified as an untrusted pointer dereference under [CWE-822]. The affected mTower code path accepts a pointer value that originates from, or is influenced by, untrusted input and dereferences it without confirming that the address is valid within the expected memory region. When the pointer references memory outside the intended range, the resulting access triggers a fault that terminates the trusted application or the mTower runtime itself.
Because mTower runs as a lightweight TEE on constrained microcontrollers, a crash inside the secure world removes the isolation and integrity services that non-secure code depends on. The impact is limited to availability; the vulnerability does not directly disclose secrets or allow code execution based on the recorded impact metrics.
Root Cause
The defect stems from missing validation of a pointer before dereference inside mTower. The upstream fix landed in commit 102d3dc75cf8e58e68e4bea54ae3c803992c91be via GitHub Pull Request #252, which introduces the necessary bounds and origin checks prior to pointer use.
Attack Vector
Exploitation requires a local attacker who can supply crafted input to the vulnerable interface and induce a user to perform an action that reaches the affected code path. No privileges are required to submit the input. Once the untrusted pointer is dereferenced, the process handling secure-world requests fails, denying service to any client relying on the TEE. The vulnerability is not remotely exploitable, and no public exploit or proof-of-concept has been reported.
See the upstream patch discussion for the specific code path and the sanitization logic introduced by the maintainers.
Detection Methods for CVE-2026-10420
Indicators of Compromise
- Unexpected crashes, resets, or watchdog-triggered reboots of IoT devices running mTower
- Trusted application (TA) invocations returning fault or abort status codes immediately after processing attacker-controlled input
- Log entries from the secure monitor indicating access violations or bus faults during TEE service calls
Detection Strategies
- Inventory firmware images and identify builds of Samsung mTower prior to commit 102d3dc75cf8e58e68e4bea54ae3c803992c91be
- Instrument development and QA builds with fault handlers that capture faulting addresses and calling contexts for TEE requests
- Fuzz mTower client interfaces with malformed pointer and handle values to surface additional dereference issues before production deployment
Monitoring Recommendations
- Forward device telemetry, crash dumps, and TEE audit events to a centralized logging pipeline for correlation
- Alert on repeated abnormal terminations of the same trusted application on a single device or across a device fleet
- Track firmware version and mTower commit hash as an asset attribute to enable rapid identification of vulnerable devices
How to Mitigate CVE-2026-10420
Immediate Actions Required
- Upgrade mTower to a build that includes commit 102d3dc75cf8e58e68e4bea54ae3c803992c91be or later
- Rebuild and reflash all downstream firmware images that embed the vulnerable mTower revision
- Restrict physical and local access to affected IoT devices until patched firmware is deployed
Patch Information
The fix is available upstream in the Samsung mTower repository through GitHub Pull Request #252, merged as commit 102d3dc75cf8e58e68e4bea54ae3c803992c91be. Integrators should pull the updated source, rebuild the secure-world binary, and validate that trusted applications continue to function against the patched runtime.
Workarounds
- Disable or gate access to trusted application entry points that accept pointer-typed parameters from non-secure clients where feasible
- Add wrapper validation in client code to reject requests carrying implausible pointer or length values before invoking the TEE
- Enforce signed firmware update policies so only builds containing the upstream fix are provisioned to devices
# Update local mTower source tree to the patched revision
git clone https://github.com/Samsung/mTower.git
cd mTower
git checkout 102d3dc75cf8e58e68e4bea54ae3c803992c91be
# Rebuild the secure-world image using the project's documented toolchain
make clean && make
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
