CVE-2025-11091: Tenda AC21 SetStaticRouteCfg sscanf buffer overflow

Vulnerability summary

CVE-2025-11091 is a high (CVSS 9.0) vulnerability in tenda ac21_firmware. EPSS estimates a 0.75% chance of exploitation in the next 30 days, higher than 54.5% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 28-09-2025
   PublishedVulnerability first disclosed.
2. 29-09-2025
   Last modifiedVulnerability information updated.

Description

A security flaw has been discovered in Tenda AC21 up to 16.03.08.16. Affected by this vulnerability is the function sscanf of the file /goform/SetStaticRouteCfg. The manipulation of the argument list results in buffer overflow. The attack can be launched remotely. The exploit has been released to the public and may be exploited.

• 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.