CVE-2026-4565: Tenda AC21 SetNetControlList formSetQosBand buffer overflow

Vulnerability summary

CVE-2026-4565 is a high (CVSS 9.0) vulnerability in tenda ac21_firmware. EPSS estimates a 1.02% chance of exploitation in the next 30 days, higher than 63% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 23-03-2026
   PublishedVulnerability first disclosed.
2. 23-03-2026
   Last modifiedVulnerability information updated.

Description

A vulnerability was detected in Tenda AC21 16.03.08.16. Impacted is the function formSetQosBand of the file /goform/SetNetControlList. Performing a manipulation of the argument list results in buffer overflow. The attack can be initiated remotely. The exploit is now public and may 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-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.