v4.4.1

⚠️ This is a patch for a low severity vulnerability. For more information visit the security advisory.

• Initializable: change the existing initializer modifier and add a new onlyInitializing modifier to prevent reentrancy risk. (#3006)

Breaking change

It is no longer possible to call an initializer-protected function from within another initializer function outside the context of a constructor. Projects using OpenZeppelin upgradeable proxies should continue to work as is, since in the common case the initializer is invoked in the constructor directly. If this is not the case for you, the suggested change is to use the new onlyInitializing modifier in the following way:

 contract A {
-    function initialize() public   initializer { ... }
+    function initialize() internal onlyInitializing { ... }
 }
 contract B is A {
     function initialize() public initializer {
         A.initialize();
     }
 }

v4.4.0

Check out the first OpenZeppelin Community Call where the team discussed everything that is included in this release.

And if you missed it, we recently announced an official bug bounty program for OpenZeppelin Contracts. Check it out!

• Ownable: add an internal _transferOwnership(address). (#2568)
• AccessControl: add internal _grantRole(bytes32,address) and _revokeRole(bytes32,address). (#2568)
• AccessControl: mark _setupRole(bytes32,address) as deprecated in favor of _grantRole(bytes32,address). (#2568)
• AccessControlEnumerable: hook into _grantRole(bytes32,address) and _revokeRole(bytes32,address). (#2946)
• EIP712: cache address(this) to immutable storage to avoid potential issues if a vanilla contract is used in a delegatecall context. (#2852)
• Add internal _setApprovalForAll to ERC721 and ERC1155. (#2834)
• Governor: shift vote start and end by one block to better match Compound's GovernorBravo and prevent voting at the Governor level if the voting snapshot is not ready. (#2892)
• GovernorCompatibilityBravo: consider quorum an inclusive rather than exclusive minimum to match Compound's GovernorBravo. (#2974)
• GovernorSettings: a new governor module that manages voting settings updatable through governance actions. (#2904)
• PaymentSplitter: now supports ERC20 assets in addition to Ether. (#2858)
• ECDSA: add a variant of toEthSignedMessageHash for arbitrary length message hashing. (#2865)
• MerkleProof: add a processProof function that returns the rebuilt root hash given a leaf and a proof. (#2841)
• VestingWallet: new contract that handles the vesting of Ether and ERC20 tokens following a customizable vesting schedule. (#2748)
• Governor: enable receiving Ether when a Timelock contract is not used. (#2748)
• GovernorTimelockCompound: fix ability to use Ether stored in the Timelock contract. (#2748)

v4.3.3

⚠️ This is a security patch. For more information visit the security advisory.

• ERC1155Supply: Handle totalSupply changes by hooking into _beforeTokenTransfer to ensure consistency of balances and supply during IERC1155Receiver.onERC1155Received calls.

v4.3.2

⚠️ This is a security patch. For more information visit the security advisory.

• UUPSUpgradeable: Add modifiers to prevent upgradeTo and upgradeToAndCall being executed on any contract that is not the active ERC1967 proxy. This prevents these functions being called on implementation contracts or minimal ERC1167 clones, in particular.

v4.3.1

⚠️ This is a security patch. For more information visit the security advisory.

• TimelockController: Add additional isOperationReady check.

v3.4.2-solc-0.7

• TimelockController: Add additional isOperationReady check.

v3.4.2

• TimelockController: Add additional isOperationReady check.

v4.3.0

Visit our blog for the full 4.3 announcement as well as Governor announcement!

• ERC2771Context: use private variable from storage to store the forwarder address. Fixes issues where _msgSender() was not callable from constructors. (#2754)
• EnumerableSet: add values() functions that returns an array containing all values in a single call. (#2768)
• Governor: added a modular system of Governor contracts based on GovernorAlpha and GovernorBravo. (#2672)
• Add an interfaces folder containing solidity interfaces to final ERCs. (#2517)
• ECDSA: add tryRecover functions that will not throw if the signature is invalid, and will return an error flag instead. (#2661)
• SignatureChecker: Reduce gas usage of the isValidSignatureNow function for the "signature by EOA" case. (#2661)

v4.2.0

Read the full announcement in the blog!

---

• ERC20Votes: add a new extension of the ERC20 token with support for voting snapshots and delegation. (#2632)
• ERC20VotesComp: Variant of ERC20Votes that is compatible with Compound's Comp token interface but restricts supply to uint96. (#2706)
• ERC20Wrapper: add a new extension of the ERC20 token which wraps an underlying token. Deposit and withdraw guarantee that the total supply is backed by a corresponding amount of underlying token. (#2633)
• Enumerables: Improve gas cost of removal in EnumerableSet and EnumerableMap.
• Enumerables: Improve gas cost of lookup in EnumerableSet and EnumerableMap.
• Counter: add a reset method. (#2678)
• Tokens: Wrap definitely safe subtractions in unchecked blocks.
• Math: Add a ceilDiv method for performing ceiling division.
• ERC1155Supply: add a new ERC1155 extension that keeps track of the totalSupply of each tokenId. (#2593)
• BitMaps: add a new BitMaps library that provides a storage efficient datastructure for uint256 to bool mapping with contiguous keys. (#2710)

Breaking Changes

• ERC20FlashMint is no longer a Draft ERC. (#2673))

How to update: Change your import paths by removing the draft- prefix from @openzeppelin/contracts/token/ERC20/extensions/draft-ERC20FlashMint.sol.

See Releases and Stability: Drafts.

v4.1.0

Read the full announcement in the blog or check out the changelog.

• IERC20Metadata: add a new extended interface that includes the optional name(), symbol() and decimals() functions. (#2561)
• ERC777: make reception acquirement optional in _mint. (#2552)
• ERC20Permit: add a _useNonce to enable further usage of ERC712 signatures. (#2565)
• ERC20FlashMint: add an implementation of the ERC3156 extension for flash-minting ERC20 tokens. (#2543)
• SignatureChecker: add a signature verification library that supports both EOA and ERC1271 compliant contracts as signers. (#2532)
• Multicall: add abstract contract with multicall(bytes[] calldata data) function to bundle multiple calls together (#2608)
• ECDSA: add support for ERC2098 short-signatures. (#2582)
• AccessControl: add a onlyRole modifier to restrict specific function to callers bearing a specific role. (#2609)
• StorageSlot: add a library for reading and writing primitive types to specific storage slots. (#2542)
• UUPS Proxies: add UUPSUpgradeable to implement the UUPS proxy pattern together with EIP1967Proxy. (#2542)