TP-Link Archer Ax21 Vulnerabilities
6 known CVEs, 1 critical, 1 in CISA's Known Exploited Vulnerabilities catalog. Last updated 2026-10-24.
Known CVEs
TP-Link Archer AX21(US)_V3_1.1.4 Build 20230219 and AX21(US)_V3.6_1.1.4 Build 20230219 are vulnerable to Buffer Overflow.
TP-Link Archer AX21 (AX1800) firmware versions before 1.1.4 Build 20230219 contained a command injection vulnerability in the country form of the /cgi-bin/luci;stok=/locale endpoint on the web management interface. Sp...
TP-Link Archer AX21 tdpServer Logging Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of TP-Lin...
TP-Link AX1800 Firmware Parsing Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of TP-Link AX18...
TP-Link AX1800 hotplugd Firewall Rule Race Condition Vulnerability. This vulnerability allows remote attackers to gain access to LAN-side services on affected installations of TP-Link Archer AX21 routers. Authenticati...
TP-Link Archer AX21 tmpServer Command 0x422 Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of ...
Commonly exposed ports
- Port 23 (Telnet) — Sends admin credentials unencrypted — a common target on older router firmware.
- Port 80 (HTTP admin panel) — The web admin UI; dangerous if remote/WAN administration is left enabled.
- Port 7547 (TR-069 (CWMP)) — ISP remote-management protocol — has been the entry point for several router botnets.
- Port 1900 (UPnP/SSDP) — Lets apps on your LAN open firewall holes automatically, sometimes without your knowledge.
Default credentials
From ProbeShield's own tested default-credential list (see probeshield.com/default-passwords/): "admin" / "tplink" or "admin" / "admin123" over HTTP.
Hardening checklist
- Disable remote (WAN-side) administration unless you specifically need it.
- Turn off UPnP unless a specific app you trust requires it.
- Turn off WPS — it can let an attacker bypass your Wi-Fi password.
- Change the default admin username and password to something unique.
- Check for a firmware update in the router’s admin panel and apply it.
- Disable Telnet/SSH management access if you don’t actively use it.
Frequently asked questions
Is my TP-Link Archer Ax21 affected by these vulnerabilities? Only if you’re running a firmware version in the affected range listed above and haven’t updated. Check your router's admin panel for its current firmware version and compare it against the ranges below.
How do I update my TP-Link Archer Ax21's firmware? Log into the router's web admin panel (usually at its local IP address) and look for a Firmware Update or System Update section, or use the vendor's mobile app if it has one.
Does ProbeShield fix these vulnerabilities for me? No — ProbeShield scans your network and tells you what it finds (open ports, default credentials, outdated firmware signals) so you know what to fix, and how. It never changes your devices’ settings.
Sources: National Vulnerability Database (NVD), CISA Known Exploited Vulnerabilities Catalog. This page lists which firmware versions are affected — it doesn't claim your specific unit is vulnerable. Check your device's current firmware version in its admin panel and compare it against the ranges above.