OpenZepplin is a library for smart contract development. In affected versions a vulnerability in TimelockController allowed an actor with the executor role to escalate privileges. Further details about the vulnerability will be disclosed at a later date. As a workaround revoke the executor role from accounts not strictly under the team's control. We recommend revoking all executors that are not also proposers. When applying this mitigation, ensure there is at least one proposer and executor remaining.
OpenZepplin is a library for smart contract development. In affected versions a vulnerability in TimelockController allowed an actor with the executor role to escalate privileges. Further details about the vulnerability will be disclosed at a later date. As a workaround revoke the executor role from accounts not strictly under the team's control. We recommend revoking all executors that are not also proposers. When applying this mitigation, ensure there is at least one proposer and executor remaining.
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.
Impact
When the verifyMultiProof, verifyMultiProofCalldata, processMultiProof, or processMultiProofCalldata 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 inadvertently 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 @openzeppelin/merkle-tree library are safe.
Patches
The problem has been patched in 4.9.2.
Workarounds
If you are using multiproofs: When constructing merkle trees hash the leaves and do not insert empty nodes in your trees. Using the @openzeppelin/merkle-tree package eliminates this issue. Do not accept user-provided merkle roots without reconstructing at least the first level of the tree. Verify the merkle tree structure by reconstructing it from the leaves.
Impact
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.
Patches
The problem has been patched in 4.9.1 by introducing opt-in frontrunning protection.
Workarounds
Submit the proposal creation transaction to an endpoint with frontrunning protection.
Credit
Reported by Lior Abadi and Joaquin Pereyra from Coinspect.
References
https://www.coinspect.com/openzeppelin-governor-dos/