Ac21 Firmware
CVE-2026-1637
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
-
AccessAuthenticate to Tenda AC21 web interface
-
ExploitSend crafted request to /goform/AdvSetMacMtuWan
-
ExecutionTrigger stack buffer overflow in fromAdvSetMacMtuWan function
-
ImpactExecute arbitrary code with device privileges
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, buffer size validation
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Tenda AC21 firmware 16.03.08.16 with /goform/AdvSetMacMtuWan endpoint accessible. Requires valid login credentials to web management interface. Exploitation possible on default-configured devices with authentication enabled. |
| Impact | CVSS 8.8 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Exploitable via remote/network. |
| Exploit ScenarioDerived | A remote attacker could exploit this flaw, stack-based buffer overflow. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAIv1 – Mar 12, 2026
Tenda AC21 firmware versions up to 16.03.08.16 contain a stack-based buffer overflow in the /goform/AdvSetMacMtuWan endpoint that can be exploited remotely by authenticated attackers to achieve arbitrary code execution. Public exploit code exists for this vulnerability, and no patch is currently available. The high CVSS score (8.8) reflects the severity of this flaw affecting device confidentiality, integrity, and availability.
Earlier versions of this analysis (1)
A vulnerability was identified in Tenda AC21 16.03.08.16. The affected element is the function fromAdvSetMacMtuWan of the file /goform/AdvSetMacMtuWan. [CVSS 8.8 HIGH]
RemediationAI
Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible. Restrict network access to the affected service where possible.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-119 (Buffer Overflow). Affects Ac21 Firmware. A vulnerability was identified in Tenda AC21 16.03.08.16. The affected element is the function fromAdvSetMacMtuWan of the file /goform/AdvSetMacMtuWan. The manipulation leads to stack-based buffer overflow. Remote exploitation of the attack is possible. The exploit is publicly available and might be used.
Know when Ac21 Firmware gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionCVE.org
A vulnerability was identified in Tenda AC21 16.03.08.16. The affected element is the function fromAdvSetMacMtuWan of the file /goform/AdvSetMacMtuWan. The manipulation leads to stack-based buffer overflow. Remote exploitation of the attack is possible. The exploit is publicly available and might be used.
Executive ViewAI
Tenda AC21 routers (model 16.03.08.16) contain a high-severity remote code execution vulnerability that allows unauthenticated attackers to compromise network infrastructure. Organizations using this device face immediate risk of network breach, data exfiltration, and operational disruption since no patch is currently available.
Implement network segmentation restricting device access to trusted networks only; deploy WAF/IDS rules blocking requests to vulnerable /goform/AdvSetMacMtuWan endpoint; disable remote administration features; place affected devices behind authenticated proxy; monitor for exploitation attempts in firewall and access logs; consider replacement with supported vendor equipment as immediate long-term mitigation.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.
Affected Products (CPE)CVE.org
More in Ac21 Firmware
View allA security vulnerability has been detected in Tenda AC21 and AC23 16.03.08.16. Rated high severity (CVSS 8.9), this vuln
Tenda AC21 V16.03.08.15 is vulnerable to Buffer Overflow via function formSetMacFilterCfg. Rated high severity (CVSS 7.5
Tenda AC21 V16.03.08.15 is vulnerable to Buffer Overflow via function via set_device_name. Rated high severity (CVSS 7.5
Tenda AC21 V16.03.08.15 is vulnerable to Buffer Overflow via /bin/httpd, function: fromSetWifiGusetBasic. Rated high sev
Tenda AC21 V 16.03.08.15 is vulnerable to Buffer Overflow via /bin/httpd, form_fast_setting_wifi_set. Rated high severit
Tenda AC21 V 16.03.08.15 is vulnerable to Buffer Overflow via /bin/httpd, setSchedWifi. Rated high severity (CVSS 7.5),
Tenda AC21 V 16.03.08.15 is vulnerable to Buffer Overflow via /bin/httpd, saveParentControlInfo. Rated high severity (CV
Tenda AC21 V 16.03.08.15 is vulnerable to Buffer Overflow via /bin/httpd, function: setSmartPowerManagement. Rated high
Tenda AC21 V 16.03.08.15 is vulnerable to Buffer Overflow via /bin/httpd, formSetDeviceName. Rated high severity (CVSS 7
Tenda AC21 V 16.03.08.15 is vulnerable to Buffer Overflow via bin/httpd, function: formSetFirewallCfg. Rated high severi
]Tenda AC21 V 16.03.08.15 is vulnerable to Buffer Overflow via /bin/httpd, function: fromSetSysTime. Rated high severity
Tenda AC21 V16.03.08.15 is vulnerable to Buffer Overflow via /bin/httpd, function: formSetQosBand. Rated high severity (
Exploit-DB