CVE-2025-15545: Backup Restore RCE Vulnerability

CVE-2025-15545 Overview

CVE-2025-15545 is a command injection vulnerability affecting the backup restore functionality in TP-Link RE605X v3 range extender devices. The backup restore function does not properly validate unexpected or unrecognized tags within the backup file. When a crafted backup file containing malicious tags is restored, the injected content is interpreted by a shell, allowing execution of arbitrary commands with root privileges.

Critical Impact

Successful exploitation allows an attacker to gain root-level command execution on the affected device, fully compromising confidentiality, integrity, and availability of the network appliance.

Affected Products

• TP-Link RE605X v3 Range Extender
• Firmware versions prior to the security patch (check TP-Link support for specific versions)

Discovery Timeline

• 2026-01-29 - CVE-2025-15545 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2025-15545

Vulnerability Analysis

This vulnerability stems from improper input validation (CWE-20) in the backup restore functionality of the TP-Link RE605X v3 firmware. The device's backup and restore feature allows administrators to export configuration settings to a file and later import them to restore the device state. However, the parser responsible for processing the backup file fails to adequately sanitize or reject unexpected or unrecognized XML/configuration tags.

When a maliciously crafted backup file containing shell metacharacters or command sequences within unrecognized tags is uploaded and restored, these tags are passed directly to a shell interpreter for processing. Since the restore operation typically runs with elevated privileges to modify system configuration, the injected commands execute with root-level access on the embedded Linux system.

The adjacent network attack vector indicates that exploitation requires network proximity to the target device, typically meaning the attacker must be on the same local network segment or have access to the device's management interface. The high attack complexity suggests that successful exploitation requires specific conditions to be met, such as having administrative access to initiate the restore operation.

Root Cause

The root cause is improper input validation (CWE-20) in the backup file parsing routine. The firmware fails to implement a strict allowlist of expected tags and does not sanitize user-controllable input before passing it to shell commands. This design flaw allows arbitrary shell metacharacters embedded in the backup file to be interpreted and executed by the underlying system shell.

Attack Vector

The attack requires an adversary with access to the device's administrative interface (adjacent network access with high privileges). The attacker would craft a malicious backup file containing command injection payloads embedded within unexpected configuration tags. When an administrator restores this backup file—either through social engineering, supply chain compromise, or if the attacker has legitimate admin access—the malicious commands execute with root privileges.

The exploitation flow involves:

1. Attacker creates a backup file with injected shell commands in unrecognized tags
2. The malicious backup file is uploaded to the device via the management interface
3. Upon restore, the parser encounters the unrecognized tags
4. Instead of rejecting or sanitizing the input, the content is passed to a shell
5. The injected commands execute with root privileges, compromising the device

Detection Methods for CVE-2025-15545

Indicators of Compromise

• Unexpected processes running on the device that were not present before a backup restore operation
• Modifications to system files or configurations that do not match the expected backup state
• Network traffic anomalies originating from the range extender to external hosts
• Unexplained changes to firewall rules or routing configurations on the device

Detection Strategies

• Monitor administrative interface access logs for backup restore operations, especially from unexpected sources
• Implement network segmentation to isolate IoT and network infrastructure devices from untrusted network segments
• Deploy network intrusion detection systems (IDS) to monitor for unusual traffic patterns from network appliances
• Audit any backup files before restoration, particularly those received from untrusted sources

Monitoring Recommendations

• Enable logging on the device's management interface if available and forward logs to a central SIEM
• Monitor for unexpected outbound connections from the range extender to external IP addresses
• Implement alerting for any firmware or configuration changes outside of scheduled maintenance windows
• Regularly review device behavior for signs of compromise such as performance degradation or unexpected reboots

How to Mitigate CVE-2025-15545

Immediate Actions Required

• Update the TP-Link RE605X v3 firmware to the latest version available from the TP-Link Firmware Download page
• Restrict access to the device's administrative interface to trusted networks and administrators only
• Do not restore backup files from untrusted or unverified sources
• Review the TP-Link FAQ for additional security guidance

Patch Information

TP-Link has released firmware updates to address this vulnerability. Users should visit the official TP-Link RE605X v3 Firmware Download page to obtain the latest firmware version. The patched firmware properly validates and sanitizes backup file contents before processing, preventing command injection through malicious tags.

Workarounds

• Isolate the device on a separate network segment with restricted access to limit exposure
• Disable remote management if not required and access the device only through a physically connected network
• Implement strong administrative credentials and enable any available multi-factor authentication
• Only use backup files that were created on the same device and stored securely
• Consider replacing the device if firmware updates are not available for your specific hardware revision

# Example: Network isolation using firewall rules to restrict management access
# Allow management interface access only from trusted admin subnet
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP