A critical issue has been identified in the Ethereum Virtual Machine, with the BLOCKHASH instruction potentially causing chain reorganization and consensus issues. Affected configurations include all versions of geth up to 1.1.3 or 1.2.2 and all eth versions before 1.0.0.
Fortunately, the risk of this occurring is low, but users should apply the corrective actions provided to avoid any potential issues. Get users can do this by running sudo apat-get update and sudo apat-get upgrade, Brew Beer users can run Brew upgrade, then brew Reinstall ethereum, and Windows users can download the most recent binary from the GitHub releases page.
For those who wish to build from source, they should simply run ‘git fetch origin && git checkout origin/master’. Ethereum have also provided instructions at https://gavofyork.gitbooks.io/turboethereum/content/chapter1.html.
No chain reorganization is expected to take place due to this issue.
