Magento LTS is the official OpenMage LTS codebase. Guest orders may be viewed without authentication using a "guest-view" cookie which contains the order's "protect_code". This code is 6 hexadecimal characters which is arguably not enough to prevent a brute-force attack. Exposing each order would require a separate brute force attack. This issue has been patched in versions 19.5.1 and 20.1.1.
https://github.com/OpenMage/magento-lts/security/advisories/GHSA-9358-cpvx-c2qp
https://github.com/OpenMage/magento-lts/releases/tag/v20.1.1
https://github.com/OpenMage/magento-lts/releases/tag/v19.5.1
https://github.com/OpenMage/magento-lts/commit/31e74ac5d670b10001f88f038046b62367f15877
https://github.com/OpenMage/magento-lts/commit/2a2a2fb504247e8966f8ffc2e17d614be5d43128