CVE-2026-1637 Tenda AC21 AdvSetMacMtuWan fromAdvSetMacMtuWan stack-based overflow
A stack-based buffer overflow in the Tenda AC21 router allows remote attackers to execute arbitrary code via the AdvSetMacMtuWan interface.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-1637?
CVE-2026-1637 is a high-severity memory corruption vulnerability in Tenda AC21, published on 29 Jan 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-1637?
It affects 1 product.
Products include Tenda Ac21 Firmware.
How do I fix CVE-2026-1637?
No fix has been published for CVE-2026-1637 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-1637 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-1637 exists.
Other vulnerabilities in Tenda AC21
- CVE-2025-9605 Tenda AC21/AC23 GetParentControlInfo stack-based overflow
- CVE-2023-24333 Command injection in n/a
- CVE-2026-4565 Tenda AC21 SetNetControlList formSetQosBand buffer overflow
- CVE-2025-13445 Tenda AC21 SetIpMacBind stack-based overflow
- CVE-2025-13446 Tenda AC21 SetSysTimeCfg stack-based overflow
Sources
Also known as GHSA-h376-wgw6-6272.