CVE-2025-15517: TP-Link Archer Auth Bypass Vulnerability

CVE-2025-15517 Overview

A missing authentication check vulnerability has been identified in the HTTP server on multiple TP-Link Archer routers, including the NX200, NX210, NX500, and NX600 models. The vulnerability exists in certain CGI endpoints that fail to properly validate authentication credentials, allowing unauthenticated users to access functionality intended only for authenticated administrators.

This authentication bypass vulnerability enables attackers on an adjacent network to perform privileged HTTP actions without valid credentials. The impact is severe as it allows unauthorized firmware uploads and configuration changes, potentially leading to complete device compromise.

Critical Impact

Unauthenticated attackers on the local network can upload malicious firmware and modify router configurations, potentially gaining persistent control over the affected device and the network it manages.

Affected Products

• TP-Link Archer NX200
• TP-Link Archer NX210
• TP-Link Archer NX500
• TP-Link Archer NX600

Discovery Timeline

• March 23, 2026 - CVE-2025-15517 published to NVD
• March 24, 2026 - Last updated in NVD database

Technical Details for CVE-2025-15517

Vulnerability Analysis

This vulnerability is classified as CWE-306: Missing Authentication for Critical Function. The HTTP server embedded in the affected TP-Link Archer routers fails to implement proper authentication checks on certain CGI endpoints. These endpoints are designed to handle sensitive administrative operations such as firmware updates and device configuration changes.

The adjacent network attack vector means that an attacker must have network adjacency to the target device—typically achieved by being connected to the same LAN segment, either via WiFi or Ethernet. Once positioned, the attacker can directly access the vulnerable CGI endpoints without providing any authentication credentials.

The vulnerability poses significant risks as successful exploitation allows an attacker to upload arbitrary firmware to the router, potentially installing backdoored firmware that provides persistent access. Additionally, configuration modifications could redirect DNS queries, disable security features, create rogue administrative accounts, or expose the device to further attacks from the internet.

Root Cause

The root cause is a missing authentication check in the HTTP server implementation. Specific CGI endpoints that should require authenticated sessions do not properly validate that incoming requests originate from authenticated users. This is a fundamental access control failure where the server processes privileged requests without verifying the caller's authorization level.

The affected endpoints handle critical functions including firmware upload operations and configuration management. The authentication validation logic that should protect these endpoints is either missing entirely or improperly implemented, creating a direct path for unauthenticated access.

Attack Vector

The attack vector requires adjacent network access, meaning the attacker must be on the same network segment as the vulnerable router. This is typically achieved by connecting to the router's WiFi network or the same LAN. From this position, the attacker can send crafted HTTP requests directly to the vulnerable CGI endpoints.

A successful attack involves identifying the vulnerable CGI endpoints on the target router, crafting HTTP requests that mimic legitimate administrative actions, and sending these requests directly to the router without authentication headers or session cookies. The router processes these requests as if they came from an authenticated administrator.

The privileged actions available through this bypass include firmware upload capabilities that could be used to install persistent backdoors, configuration changes that could expose the network to further attacks, and potential credential extraction or network traffic interception.

Detection Methods for CVE-2025-15517

Indicators of Compromise

• Unexpected firmware version changes on affected TP-Link Archer devices
• Unauthorized configuration modifications such as DNS server changes, new port forwarding rules, or disabled security features
• HTTP requests to administrative CGI endpoints from unexpected source IP addresses on the local network
• Unusual outbound traffic patterns from the router indicating potential command and control activity

Detection Strategies

• Monitor network traffic for HTTP requests to known administrative CGI endpoints on TP-Link routers that lack proper session authentication headers
• Implement network access controls to segment IoT and network infrastructure devices from general user segments
• Deploy network monitoring solutions to detect unauthorized configuration change attempts on network infrastructure
• Regularly audit router firmware versions and configurations against known-good baselines

Monitoring Recommendations

• Enable logging on the router if supported and forward logs to a centralized SIEM for analysis
• Monitor for any firmware update activities that are not authorized through change management processes
• Implement network-level monitoring to detect reconnaissance activities targeting router management interfaces
• Consider placing critical network infrastructure devices on isolated management VLANs with strict access controls

How to Mitigate CVE-2025-15517

Immediate Actions Required

• Download and apply the latest firmware updates from TP-Link for all affected Archer models (NX200, NX210, NX500, NX600)
• Restrict access to the router's web management interface to trusted management stations only
• Implement network segmentation to limit which devices can reach the router's administrative interface
• Disable remote management features if not required

Patch Information

TP-Link has released firmware updates to address this vulnerability. Users should download the latest firmware for their specific model from the official TP-Link support pages:

• TP-Link Archer NX200 Firmware
• TP-Link Archer NX210 Firmware
• TP-Link Archer NX500 Firmware
• TP-Link Archer NX600 Firmware

For additional security guidance, refer to the TP-Link FAQ on Security.

Workarounds

• Implement access control lists (ACLs) at the network level to restrict which devices can communicate with the router's management interface
• Place affected routers behind a firewall that can inspect and block unauthorized requests to administrative endpoints
• Use a separate, isolated management network for accessing router administration interfaces
• Consider replacing affected devices with patched units or alternative models if immediate patching is not possible

# Example: Network segmentation using VLAN configuration
# Create a management VLAN and restrict router admin access
# This example is for reference - actual commands vary by switch vendor

# On managed switch, create management VLAN
vlan 100 name MGMT_VLAN

# Assign management workstation port to VLAN 100
interface eth1/1
  switchport access vlan 100

# Configure ACL to restrict management interface access
ip access-list extended ROUTER_MGMT_ACL
  permit tcp 192.168.100.0/24 host 192.168.1.1 eq 80
  permit tcp 192.168.100.0/24 host 192.168.1.1 eq 443
  deny tcp any host 192.168.1.1 eq 80
  deny tcp any host 192.168.1.1 eq 443