CVE-2026-18167 in Archer AX55
Summary
by MITRE • 09/04/2026
A stack-based buffer overflow vulnerability exists in the EasyMesh module of TP-Link Archer AX55 v4. When Mesh mode is enabled, a LAN attacker may submit crafted input that causes the easymesh daemon to crash and may potentially achieve remote code execution on the device.
Successful exploitation may cause the EasyMesh daemon to crash and may potentially allow remote code execution when Mesh mode is enabled. This may result in high impact to the confidentiality, integrity, and availability of the affected device.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified as a stack-based buffer overflow within the EasyMesh module of TP-Link Archer AX55 v4 represents a critical security flaw that compromises the structural integrity of memory management during runtime operations. This specific type of vulnerability arises when an application writes more data to a fixed-size block of memory allocated on the call stack than it can hold, thereby overwriting adjacent memory locations. In this particular instance, the easymesh daemon fails to adequately validate or bound-check user-supplied input received from network interfaces before processing it. When Mesh mode is enabled, the device actively participates in mesh networking protocols, which inherently requires handling complex and potentially untrusted data structures transmitted between nodes. The lack of rigorous boundary checks allows an attacker to craft specific packets containing oversized payloads that exceed the allocated stack space for buffer variables within the daemon's execution context.
From a technical perspective, this overflow overwrites critical control flow data stored on the stack, such as return addresses or saved frame pointers. By carefully crafting the input payload, an attacker can manipulate these overwritten values to redirect program execution to arbitrary code injected into the memory space. This mechanism is consistent with Common Weakness Enumeration standard CWE-121, which describes a stack-based buffer overflow where data written exceeds the bounds of the destination buffer on the call stack. The exploitation vector for this vulnerability is classified under network access via LAN, aligning with ATT&CK technique T1046 (Network Service Discovery) and potentially T1190 (Exploit Public-Facing Application), as it targets a service exposed to local network segments rather than requiring physical proximity or remote internet exposure. The presence of this flaw indicates insufficient input sanitization within the firmware's mesh management subsystem, reflecting a deviation from secure coding practices that mandate strict validation of all external inputs before processing.
The operational impact of successfully exploiting this vulnerability is severe and multifaceted. Initially, the immediate consequence is the crash or termination of the easymesh daemon due to memory corruption triggering segmentation faults or similar protection mechanisms. This denial of service disrupts mesh network functionality, leading to connectivity issues for devices relying on the extended wireless coverage provided by the mesh system. However, the more critical risk lies in the potential for remote code execution. If an attacker successfully controls the instruction pointer through precise buffer overflow techniques, they can execute arbitrary commands with the privileges granted to the easymesh daemon process. This could lead to a complete compromise of the router's operating environment, allowing the adversary to exfiltrate sensitive network traffic, modify routing tables, install persistent backdoors, or pivot attacks into other segments of the local area network. Such an outcome directly impacts confidentiality by exposing private data, integrity by allowing unauthorized modifications to device configuration and firmware state, and availability by destabilizing critical networking services.
Mitigation strategies for this vulnerability primarily involve applying vendor-provided security patches that update the EasyMesh module with proper input validation routines. Developers must implement strict length checks on all incoming network packets destined for mesh processing functions to ensure they do not exceed predefined buffer limits. Additionally, enabling compiler-level protections such as stack canaries (stack smashing protection), Address Space Layout Randomization, and non-executable memory pages can significantly raise the barrier for successful exploitation by detecting overflows at runtime or preventing code execution in data segments. For end-users, immediate action should include updating the router firmware to the latest version released by TP-Link that addresses this specific CVE. Until patches are applied, network segmentation strategies such as isolating IoT devices on a separate VLAN can limit the blast radius of any potential exploitation attempts originating from compromised endpoints within the LAN environment.