OpenZeppelin Contracts is a library for smart contract development. A merge issue when porting the 5.0.1 patch to the 4.9 branch caused a line duplication. In the version of `Multicall.sol` released in `@openzeppelin/contracts@4.9.4` and `@openzeppelin/contracts-upgradeable@4.9.4`, all subcalls are executed twice. Concretely, this exposes a user to unintentionally duplicate operations like asset transfers. The duplicated delegatecall was removed in version 4.9.5. The 4.9.4 version is marked as deprecated. Users are advised to upgrade. There are no known workarounds for this issue.

OpenZeppelin Contracts is a library for smart contract development. Starting in version 4.7.0 and prior to version 4.9.2, when the `verifyMultiProof`, `verifyMultiProofCalldata`, `procesprocessMultiProof`, or `processMultiProofCalldat` functions are in use, it is possible to construct merkle trees that allow forging a valid multiproof for an arbitrary set of leaves. A contract may be vulnerable if it uses multiproofs for verification and the merkle tree that is processed includes a node with value 0 at depth 1 (just under the root). This could happen inadvertedly for balanced trees with 3 leaves or less, if the leaves are not hashed. This could happen deliberately if a malicious tree builder includes such a node in the tree. A contract is not vulnerable if it uses single-leaf proving (`verify`, `verifyCalldata`, `processProof`, or `processProofCalldata`), or if it uses multiproofs with a known tree that has hashed leaves. Standard merkle trees produced or validated with the @openzep…

OpenZeppelin Contracts is a library for smart contract development. By frontrunning the creation of a proposal, an attacker can become the proposer and gain the ability to cancel it. The attacker can do this repeatedly to try to prevent a proposal from being proposed at all. This impacts the `Governor` contract in v4.9.0 only, and the `GovernorCompatibilityBravo` contract since v4.3.0. This problem has been patched in 4.9.1 by introducing opt-in frontrunning protection. Users are advised to upgrade. Users unable to upgrade may submit the proposal creation transaction to an endpoint with frontrunning protection as a workaround.

OpenZeppelin Contracts is a library for secure smart contract development. A function in the implementation contract may be inaccessible if its selector clashes with one of the proxy's own selectors. Specifically, if the clashing function has a different signature with incompatible ABI encoding, the proxy could revert while attempting to decode the arguments from calldata. The probability of an accidental clash is negligible, but one could be caused deliberately and could cause a reduction in availability. The issue has been fixed in version 4.8.3. As a workaround if a function appears to be inaccessible for this reason, it may be possible to craft the calldata such that ABI decoding does not fail at the proxy and the function is properly proxied through.

OpenZeppelin Contracts is a library for secure smart contract development. The proposal creation entrypoint (`propose`) in `GovernorCompatibilityBravo` allows the creation of proposals with a `signatures` array shorter than the `calldatas` array. This causes the additional elements of the latter to be ignored, and if the proposal succeeds the corresponding actions would eventually execute without any calldata. The `ProposalCreated` event correctly represents what will eventually execute, but the proposal parameters as queried through `getActions` appear to respect the original intended calldata. This issue has been patched in 4.8.3. As a workaround, ensure that all proposals that pass through governance have equal length `signatures` and `calldatas` parameters.

OpenZeppelin Contracts is a library for secure smart contract development. The ERC721Consecutive contract designed for minting NFTs in batches does not update balances when a batch has size 1 and consists of a single token. Subsequent transfers from the receiver of that token may overflow the balance as reported by `balanceOf`. The issue exclusively presents with batches of size 1. The issue has been patched in 4.8.2.

OpenZeppelin Contracts is a library for secure smart contract development. Before version 4.4.1 but after 3.2.0, initializer functions that are invoked separate from contract creation (the most prominent example being minimal proxies) may be reentered if they make an untrusted non-view external call. Once an initializer has finished running it can never be re-executed. However, an exception put in place to support multiple inheritance made reentrancy possible in the scenario described above, breaking the expectation that there is a single execution. Note that upgradeable proxies are commonly initialized together with contract creation, where reentrancy is not feasible, so the impact of this issue is believed to be minor. This issue has been patched, please upgrade to version 4.4.1. As a workaround, avoid untrusted external calls during initialization.

OpenZeppelin Contracts is a library for secure smart contract development. The functions `ECDSA.recover` and `ECDSA.tryRecover` are vulnerable to a kind of signature malleability due to accepting EIP-2098 compact signatures in addition to the traditional 65 byte signature format. This is only an issue for the functions that take a single `bytes` argument, and not the functions that take `r, v, s` or `r, vs` as separate arguments. The potentially affected contracts are those that implement signature reuse or replay protection by marking the signature itself as used rather than the signed message or a nonce included in it. A user may take a signature that has already been submitted, submit it again in a different form, and bypass this protection. The issue has been patched in 4.7.3.

OpenZeppelin Contracts is a library for secure smart contract development. Contracts using the cross chain utilities for Arbitrum L2, `CrossChainEnabledArbitrumL2` or `LibArbitrumL2`, will classify direct interactions of externally owned accounts (EOAs) as cross chain calls, even though they are not started on L1. This issue has been patched in v4.7.2. Users are advised to upgrade. There are no known workarounds for this issue.

OpenZeppelin Contracts is a library for secure smart contract development. The target contract of an EIP-165 `supportsInterface` query can cause unbounded gas consumption by returning a lot of data, while it is generally assumed that this operation has a bounded cost. The issue has been fixed in v4.7.2. Users are advised to upgrade. There are no known workarounds for this issue.