CVE-2026-4861
CVE-2026-4861: Buffer Overflow in Wavlink WL-NU516U1
Executive Summary
CVE-2026-4861 is a high severity vulnerability affecting software systems. It is classified as Memory Buffer Overflow. Ensure your systems and dependencies are patched immediately to mitigate exposure risks.
Precogs AI Insight
"Precogs AI detected this vulnerability pattern in Memory Buffer Overflow implementations. The pattern deviates from documented secure coding standards, suggesting a high likelihood of exploitation if unpatched."
Summary
A high-severity stack-based buffer overflow vulnerability (CVE-2026-4861) has been identified in the Wavlink WL-NU516U1 network device, firmware version 260227. The vulnerable request handler fails to validate input size before performing memory copy operations (CWE-121).
Technical Details
The issue is classified under CWE-121 (Stack-based Buffer Overflow) and the parent class CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The device firmware uses unsafe C library functions (such as strcpy or sprintf) to process incoming network requests without validating that the input fits within the allocated stack buffer.
When an oversized payload is sent to the vulnerable endpoint, it overflows the stack buffer, overwriting the saved return address and potentially other critical stack variables.
Exploitation Context
- Vector: Remote / Network-based
- Authentication: Not required
- Complexity: Low
- Impact: High (Confidentiality, Integrity, and Availability)
IoT and network devices typically run on ARM or MIPS processors with minimal memory protections (often lacking ASLR, DEP, or stack canaries), making exploitation significantly easier than on desktop or server platforms.
Remediation
Users of Wavlink WL-NU516U1 should immediately:
- Contact the vendor for an updated firmware patch addressing this buffer overflow condition.
- Restrict access to the device's web management interface to trusted networks only, ensuring it is not exposed to the public internet.
- Deploy network-level intrusion prevention systems (IPS) with signatures designed to detect anomalous payload sizes targeting the device.
Precogs AI Integration
The Precogs AI Binary Security Platform scans IoT firmware binaries across ARM, MIPS, and x86 architectures to identify unsafe memory operations. By statically simulating execution paths, Precogs detects bounds-checking failures and unsafe function usage patterns before firmware is deployed to edge devices.