laceous

Due to lack of interest (both my own and based on the number of downloads) this plugin will not be updated for WP 3.0
WordPress’ auth cookies include a built-in expiration date (either 2 or 14 days depending on if the ‘Remember Me’ option is checked). Even if you remove the client-side cookie (by manually logging out or just closing your browser if ‘Remember Me’ wasn’t checked when logging in) the data that was stored within the cookie is still valid until the expiration date is reached.
This could be an issue if someone managed to “steal” your cookie(s). They would still be able to access your website for some time into the future.
This plugin will immediately invalidate your auth cookies when you manually log out. This, of course, also means that you have to manually click ‘Log out’ for this plugin to work properly (you can’t just close your browser to remove any cookies that expire at the end of the session). This won’t prevent session hijacking, but should limit the amount of time that an attacker can access your website.

Invalidate Logged Out Cookies

This plugin will immediately invalidate your auth cookies when you manually log out.

Julio Potier

Grégory Viguier

With this plugin you can now add a real log in/logout item menu with autoswitch when user is logged in or not. 
Nonce token is present on logout item. 
2 titles, one for ‘log in’ and one for ‘logout’ can be set up. 
Also, you can set the redirecion page you want, just awesome.

Login Logout Menu

This plugin (still) works great.

However be aware that it's not compatible with PHP 8 or newer, the latest PHP version this plugin will work with is 7.4. This is due to its use of create_function, which has been deprecated since PHP 7.2 and removed as of PHP 8. This should be replaced with an anonymous function, which is easy enough. But I haven't tested this myself, so I don't know if that's the only incompatibility with PHP 8+.

Works great, but...

You can now add a correct login & logout link in your WP menus.

Invalidate Logged Out Cookies vs Login Logout Menu