Uninitialized Storage Pointer
Uninitialized Storage Pointer can lead to smart contract vulnerabilities. Data is stored in the EVM as either storage, memory, or calldata. It is important that they are well understood and correctly initialized.
As of Solidity 0.5.0, uninitialized storage pointers are no longer an issue since contracts with uninitialized storage pointers will no longer compile. This being said, it's still important to understand what storage pointers you should be using in certain situations.
Sources
https://swcregistry.io/docs/SWC-109
https://github.com/sigp/solidity-security-blog#storage
https://solidity.readthedocs.io/en/latest/types.html#data-location
https://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
https://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-in-memory