The Litecoin development team has announced a new core software release, urging all node operators and wallet users to upgrade immediately. The latest version, Litecoin Core v0.21.5.5, includes important security updates aimed at addressing vulnerabilities discovered earlier this year.
In a post on X, the official Litecoin account confirmed the release is now available. The patch version focuses on MWEB (Mimblewimble Extension Block) consensus hardening, node reliability improvements, wallet and mining fixes, along with build and test updates. The team said all users are strongly advised to upgrade as soon as possible.
Key Changes in v0.21.5.5
The release includes several notable changes. One major fix increases the maximum P2P protocol message length to 32 MB, ensuring valid MWEB blocks and messages fit under the message-size limit. Developers also prevented the reading of the previous block from disk when constructing HogEx transactions. The update also avoids including MWEB transactions in candidate blocks when their input and output commitments would sum to zero.
Additional improvements include fixes for MWEB validation and state-handling issues. Tests were expanded for MWEB P2P messages, duplicate pegins, crash recovery, mutated blocks, mining, and wallet or RPC behavior. The MWEB PMMR rewind corruption was fixed, along with improved MMR file write durability. A transaction index consistency issue, which could occur if writing block data failed after the index commit, has also been resolved.
