magento-lts cross-site request forgery in OAuth authorization confirm

Description

OpenMage Magento LTS before 20.18.2 and 21.0.0-beta1 before 21.0.0-beta3 contains a cross-site request forgery vulnerability in the admin and storefront OAuth confirm and confirmSimple actions, which accept GET requests without form-key validation. Attackers holding OAuth consumer credentials can lure a logged-in administrator or customer to a crafted confirm URL that authorizes the attacker's request token, then exchange it at /oauth/token for a persistent REST API access token bound to the victim.

Reported fixed versions

20.18.2, 21.0.0-beta3