CVE-2026-1637: Tenda AC21 AdvSetMacMtuWan fromAdvSetMacMtuWan stack-based overflow

Vulnerability summary

CVE-2026-1637 is a high (CVSS 9.0) vulnerability in tenda ac21_firmware. EPSS estimates a 0.71% chance of exploitation in the next 30 days, higher than 53% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 29-01-2026
   PublishedVulnerability first disclosed.
2. 23-02-2026
   Last modifiedVulnerability information updated.

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.

• CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferThe product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
• CWE-121Stack-based Buffer OverflowA stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).