CVE-2026-10828 Overview
CVE-2026-10828 is a format string vulnerability [CWE-134] in the Moxa NPort W2150A-W4/W2250A-W4 Series wireless serial device servers running firmware version 1.5 and prior. The flaw resides in the alias parameter on the Serial Param configuration page of the web management service. An authenticated attacker can submit crafted format specifiers to trigger out-of-bounds memory reads. Successful exploitation discloses sensitive memory contents and can reveal critical memory addresses, enabling Address Space Layout Randomization (ASLR) bypass.
Critical Impact
Attackers with high-privilege access to the web interface can leak process memory and recover address layout information, weakening exploit mitigations and enabling chained attacks against the device firmware.
Affected Products
- Moxa NPort W2150A-W4 Series, firmware version 1.5 and prior
- Moxa NPort W2250A-W4 Series, firmware version 1.5 and prior
- Serial Param configuration page in the embedded web service
Discovery Timeline
- 2026-06-16 - CVE-2026-10828 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2026-10828
Vulnerability Analysis
The defect occurs because the web service passes user-supplied data from the alias parameter directly into a format string function without sanitization. When format specifiers such as %x, %s, or %p are embedded in the input, the underlying C runtime interprets them as conversion directives. The function then reads from the process stack or arbitrary memory locations to satisfy the format arguments. The resulting output is reflected back through the configuration interface, leaking the contents of those memory regions to the attacker.
Because the NPort series exposes the configuration page over the network, the attack reaches the device without local access. The attacker must hold administrative credentials, which constrains opportunistic exploitation but does not prevent abuse from compromised operator accounts or insiders.
Root Cause
The root cause is improper neutralization of externally controlled format strings [CWE-134] in the handler for the alias field. The firmware lacks input validation and uses the parameter as the format argument rather than as data passed to a %s token. Combined with the lack of stack canaries or argument count checks, this allows controlled disclosure of stack frames and pointers.
Attack Vector
An authenticated user submits a crafted POST or GET request to the Serial Param configuration endpoint with the alias parameter set to a string containing format specifiers. The web service processes the value through the vulnerable formatting routine. The attacker reads the reflected output, repeats with adjusted specifiers, and reconstructs memory addresses. These addresses can be used to defeat ASLR and prepare a second-stage exploit, including the companion stack-based buffer overflow tracked alongside this advisory.
No verified public proof-of-concept code is available. See the Moxa Security Advisory MPSA-261910 for vendor technical details.
Detection Methods for CVE-2026-10828
Indicators of Compromise
- Requests to the Serial Param configuration page containing %x, %s, %p, %n, or %.Nx sequences in the alias field
- Unusual or non-printable strings returned in configuration responses or stored alias values
- Repeated authenticated configuration changes from a single source within short time windows
- Configuration audit logs showing alias values that do not match operator naming conventions
Detection Strategies
- Inspect HTTP/HTTPS traffic to NPort management interfaces for format specifiers in POST bodies and query parameters
- Deploy network signatures that match alias= parameters containing % characters followed by conversion letters
- Correlate administrative logins with subsequent configuration writes to identify credential abuse
Monitoring Recommendations
- Forward NPort device syslog to a centralized log platform and alert on configuration changes to serial port parameters
- Restrict management traffic to a dedicated VLAN and monitor that segment for unexpected sources
- Track firmware versions across the fleet to identify devices still running 1.5 or earlier
How to Mitigate CVE-2026-10828
Immediate Actions Required
- Apply the firmware update referenced in Moxa advisory MPSA-261910 as soon as it is available for your model
- Rotate administrative credentials on all NPort W2150A-W4 and W2250A-W4 devices
- Remove management access from untrusted networks and the public internet
- Audit existing alias values for embedded format specifiers and reset suspicious entries
Patch Information
Moxa published advisory MPSA-261910 covering CVE-2026-10828 and the related stack-based buffer overflow. Consult the advisory for the fixed firmware version applicable to your hardware revision and follow the vendor upgrade procedure.
Workarounds
- Place NPort devices behind a firewall that permits management connections only from trusted administrator workstations
- Disable the web configuration interface where serial console or CLI management is sufficient
- Enforce least privilege on device accounts and reduce the number of users with configuration rights
- Use a jump host with session recording for all administrative access to NPort devices
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
