In all version of Odoo on ubuntu you can install fail2ban and create a jail with the custom filter.

in the case above do the following (Assuming you have nginx)

1. install fail2ban

2. Create a Fail2ban filter for GET /shop/cart/update
  nano /etc/fail2ban/filter.d/nginx-cart-update.conf 

In the file add this lines:
[Definition]

failregex = ^<HOST> -.*"(GET|POST) /shop/cart/update.*$

3.  Open or create the jail configuration file, e.g., nano /etc/fail2ban/jail.local, and add the following:

[nginx-cart-update]

enabled = true

port = http,https

filter = nginx-cart-update

logpath = /var/log/nginx/access.log  # Update this if your access log is located elsewhere

maxretry = 5  # Adjust the threshold as needed

bantime = 3600  # Adjust the ban time as needed

4. Restart fail2ban

sudo systemctl restart fail2ban

Now, Fail2ban will monitor your Nginx logs and ban IPs that attempt multiple "GET /shop/cart/update" requests, which helps mitigate this brute-force attack.

Thank you
- Datalabsystems.com