Use of weak cryptographic key in TP-Link Archer C7

The primary impact of CVE-2026-5363 is the potential for an attacker to gain unauthorized access to the router's administrative interface. By intercepting network traffic and performing a brute-force or factorization attack against the weak RSA-1024 key, an attacker can recover the plaintext administrator password. This allows them to modify router settings, redirect traffic, install malicious firmware, or use the router as a pivot point to attack other devices on the network. The blast radius extends to all devices connected to the compromised router, making it a significant security risk, especially in home and small office environments.

Home and small office users who rely on TP-Link Archer C7 v5 and v5.8 routers with firmware builds up to 20220715 are at risk. Shared hosting environments where routers are managed by the provider are also vulnerable. Users who have not updated their router firmware are particularly susceptible.

• linux / server: Monitor network traffic using tools like tcpdump or Wireshark for attempts to capture login credentials. Filter for traffic to the router's web interface (typically port 80 or 443).

tcpdump -i <interface> 'port 80 or port 443' -w capture.pcap

• generic web: Use curl to test the router's login page and observe the encryption method used. Look for signs of weak RSA encryption in the captured traffic.

curl -v https://<router_ip>/login

• generic web: Examine router access logs for failed login attempts and unusual activity. Look for patterns that might indicate a brute-force attack.

1. 2026-04-15Disclosure

   disclosure

1. Reservado2026-04-01
2. Publicada2026-04-15
3. Modificada2026-04-16
4. EPSS atualizado2026-04-23

The primary mitigation for CVE-2026-5363 is to upgrade the TP-Link Archer C7 router to a firmware version that addresses the weak encryption. Check the TP-Link support website for updated firmware releases. As an interim measure, monitor network traffic for suspicious activity, particularly attempts to intercept or replay login credentials. Consider implementing network segmentation to limit the potential impact of a compromised router. After upgrading, verify the password recovery mechanism is no longer vulnerable by attempting to intercept and decrypt login traffic.