CVE-2021-31755KEV · OVERDUE

Tenda AC11 Router Stack Buffer Overflow Vulnerability

Critical · published May 7, 2021

Patch now

Confirmed exploited, and the score agrees

CVSS calls it critical at 9.8. It is confirmed in active exploitation. It sits in the 99.7th percentile for exploit probability.

1754
days past CISA
deadline
CVSS v3.1
9.8
EPSS
87%
Percentile
99.7
In the wild
Confirmed
What it is

🚨 A stack buffer overflow on Tenda AC11 routers is like leaving the front door wide open — a crafted request could let attackers execute any code they want! 🔥 Think of it as a hotel where anyone can slip a key into the lock to access a suite without any verification. That’s what happens here when the router blindly accepts a crafted POST request without checking the contents. This vulnerability could allow an attacker to run any code on your router, potentially giving them control over your network. They could intercept your traffic, steal sensitive data, or even launch attacks on other devices connected to your network. The consequences are absolutely devastating for both your security and privacy.

Put simply

Think of it as a hotel where anyone can slip a key into the lock to access a suite without any verification. That’s what happens here when the router blindly accepts a crafted POST request without checking the contents. The flaw exists in the '/goform/setmac' endpoint of Tenda AC11 devices with certain firmware versions. A stack buffer overflow allows attackers to exploit this endpoint by sending a specially crafted POST request, leading to arbitrary code execution.

What to do

This vulnerability could allow an attacker to run any code on your router, potentially giving them control over your network. They could intercept your traffic, steal sensitive data, or even launch attacks on other devices connected to your network. The consequences are absolutely devastating for both your security and privacy. To protect your devices, immediately update the firmware to the latest version available on Tenda's website. Ensure that your network settings are secure, and consider changing any default passwords. Regularly check for firmware updates to stay protected! You've got this! Follow these steps and you’ll have your network secured in no time. 🛡️

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.86777 · 99.7th percentile
Published
2021-05-07T22:01Z
KEV added
2021-11-03 · due 2021-11-17
EPSS history
Timeline
  • 03 NOV 00:00Z
    Added to CISA KEV — remediate by Nov 17
    kev
  • 07 MAY 22:01Z
    An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN
    cvelistv5