CVE-2025-9377: TP-Link TL-WR841N Firmware RCE Vulnerability

CVE-2025-9377 Overview

An authenticated remote command execution (RCE) vulnerability exists in the Parental Control page on TP-Link Archer C7(EU) V2 and TL-WR841N/ND(MS) V9 routers. This command injection flaw (CWE-78) allows authenticated attackers to execute arbitrary system commands on the underlying operating system through the router's web management interface.

This vulnerability affects Archer C7(EU) V2 firmware versions before 241108 and TL-WR841N/ND(MS) V9 firmware versions before 241108. Critically, both affected products have reached End-of-Life (EOL) status, meaning ongoing security support is limited.

Critical Impact

This vulnerability is actively exploited in the wild and has been added to CISA's Known Exploited Vulnerabilities (KEV) catalog. Authenticated attackers can achieve complete device compromise, potentially using the router as a pivot point for further network attacks.

Affected Products

• TP-Link Archer C7(EU) V2 (firmware versions before 241108)
• TP-Link TL-WR841N(MS) V9 (firmware versions before 241108)
• TP-Link TL-WR841ND(MS) V9 (firmware versions before 241108)

Discovery Timeline

• 2025-08-29 - CVE-2025-9377 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-9377

Vulnerability Analysis

This vulnerability is classified as an OS Command Injection (CWE-78) vulnerability in the Parental Control functionality of affected TP-Link routers. The Parental Control page processes user-supplied input without adequate sanitization, allowing authenticated users to inject shell commands that are executed by the underlying Linux-based operating system.

While authentication is required to exploit this vulnerability, the default or weak credentials commonly found on consumer routers significantly lower the barrier to exploitation. Once exploited, an attacker gains the ability to execute commands with root-level privileges on the router, enabling complete device takeover.

The vulnerability is particularly concerning given that both affected product lines have reached End-of-Life status, limiting the availability of future security patches and making replacement the recommended long-term solution.

Root Cause

The root cause of this vulnerability lies in improper input validation within the Parental Control feature's web interface handler. User-supplied parameters are passed directly to system shell commands without proper sanitization or escaping, enabling command injection attacks. The affected code fails to implement appropriate input validation controls such as allowlisting acceptable characters or using parameterized command execution.

Attack Vector

The attack vector is network-based, requiring the attacker to have authenticated access to the router's web management interface. An attacker can exploit this vulnerability through the following general approach:

1. Gain authenticated access to the router's administrative interface (using default, weak, or stolen credentials)
2. Navigate to the Parental Control configuration page
3. Inject malicious shell commands through vulnerable input fields
4. The injected commands execute with root privileges on the router's embedded Linux system

The vulnerability enables complete compromise of the router, including the ability to modify firmware, intercept network traffic, establish persistence, and pivot to attack other devices on the network.

Detection Methods for CVE-2025-9377

Indicators of Compromise

• Unexpected outbound connections from the router to unknown IP addresses
• Unusual processes running on the router if shell access is available for inspection
• Modified router configurations, especially in Parental Control settings
• New or unauthorized user accounts on the router's management interface
• Unexplained router reboots or performance degradation

Detection Strategies

• Monitor network traffic for anomalous connections originating from router IP addresses
• Implement network-based intrusion detection rules to identify command injection patterns in HTTP traffic to router management interfaces
• Audit router configurations regularly for unauthorized changes
• Deploy network segmentation to limit exposure of router management interfaces

Monitoring Recommendations

• Enable logging on the router if supported and forward logs to a SIEM solution
• Monitor for authentication attempts to router management interfaces from unusual source IPs
• Track firmware version inventory and alert on devices running vulnerable versions
• Implement network traffic analysis to detect lateral movement from compromised routers

How to Mitigate CVE-2025-9377

Immediate Actions Required

• Update affected devices to firmware version 241108 or later immediately
• Change default administrator credentials to strong, unique passwords
• Restrict management interface access to trusted IP addresses only
• Consider disabling remote management if not required
• Plan for device replacement as both product lines are End-of-Life

Patch Information

TP-Link has released firmware version 241108 which addresses this vulnerability. However, as both affected product lines have reached End-of-Life status, TP-Link recommends purchasing newer products to ensure better performance and security.

For organizations that cannot immediately replace affected devices, patches are available through the TP-Link Security FAQ. Additional security information is available at the TP-Link Security Issues FAQ.

Given this vulnerability's inclusion in CISA's Known Exploited Vulnerabilities catalog, federal agencies and organizations following CISA guidance should prioritize remediation within the mandated timeframe.

Workarounds

• Disable remote management access to the router's web interface
• Implement firewall rules to restrict access to the management interface to specific trusted IP addresses
• Segment network architecture to isolate management interfaces from untrusted networks
• Deploy a VPN requirement for administrative access if remote management is necessary
• Monitor for exploitation attempts while awaiting patch deployment or device replacement

# Example: Restrict management access via firewall (if supported)
# Consult router documentation for specific CLI commands
# Block external access to management port (typically 80/443)
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP