{"id":9507,"date":"2025-03-09T13:18:26","date_gmt":"2025-03-09T12:18:26","guid":{"rendered":"https:\/\/wsj-crypto.com\/?p=9507"},"modified":"2025-03-09T13:18:26","modified_gmt":"2025-03-09T12:18:26","slug":"critical-update-addressing-blockhash-instruction-concerns-in-c-and-go-clients","status":"publish","type":"post","link":"https:\/\/wsj-crypto.com\/index.php\/2025\/03\/09\/critical-update-addressing-blockhash-instruction-concerns-in-c-and-go-clients\/","title":{"rendered":"Critical Update: Addressing BLOCKHASH Instruction Concerns in C++ and Go Clients"},"content":{"rendered":"<p><\/p>\n<div id=\"\">\n<p class=\"chakra-text css-gi02ar\"><b>Overview: <!-- --><\/b>Flawed execution of BLOCKHASH may instigate a chain reorganization resulting in consensus complications<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><b>Implicated configurations: <!-- --><\/b>All geth editions up to 1.1.3 and 1.2.2. All eth editions preceding 1.0.0.<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><b>Probability: <!-- --><\/b>Low<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><b>Impact Level: <!-- --><\/b>Medium<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><b>Consequence: <!-- --><\/b>Medium<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><b>Insights:<!-- --><\/b> Both C++ (eth) and Go (geth) clients feature a flawed execution of a rare scenario in the Ethereum virtual machine, namely determining which chain the BLOCKHASH command employs to fetch a block hash. This scenario is extremely rare to occur on an active network as it would only activate in specific forms of chain reorganizations (a contract performing BLOCKHASH(N &#8211; 1) where N represents the top of a non-canonical subchain that is not yet restructured to become the canonical (best\/longest) chain but will be post block processing).<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\">pyethereum remains unaffected.<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><b>Influence on anticipated chain reorganization depth: <!-- --><\/b>none<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><b>Corrective measures undertaken by Ethereum<!-- --><\/b>: Issuance of hotfixes as specified below.<!-- --><\/p>\n<p><!-- --><\/p>\n<h3 class=\"chakra-heading css-145upk7\" id=\"geth\"><strong>Geth:<!-- --><\/strong><\/h3>\n<p><!-- --><strong>PPA<!-- --><\/strong>: sudo apt-get update then sudo apt-get upgrade<br \/>\n<!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><strong>Brew<!-- --><\/strong>: brew update then brew reinstall ethereum<!-- --><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><strong>Windows<!-- --><\/strong>: acquire the updated binary from <!-- --><a target=\"_blank\" rel=\"noopener\" class=\"chakra-link css-ug8vf0\" href=\"https:\/\/github.com\/ethereum\/go-ethereum\/releases\/tag\/v1.2.3\"\/><a target=\"_blank\" rel=\"noopener\" class=\"chakra-link css-ug8vf0\" href=\"https:\/\/github.com\/ethereum\/go-ethereum\/releases\/tag\/v1.2.3\">https:\/\/github.com\/ethereum\/go-ethereum\/releases\/tag\/v1.2.3<!-- --><\/a><\/p>\n<p><!-- --><\/p>\n<p class=\"chakra-text css-gi02ar\"><strong>Compiling from source:<!-- --><\/strong><\/p>\n<p><!-- --><\/p>\n<div class=\"chakra-stack css-1uyok63\">\n<pre>git fetch origin &amp;&amp; git checkout origin\/master<!-- --><\/pre>\n<\/div>\n<p><!-- --><br \/>\n<!-- --><br \/>\n<!-- --><br \/>\n<!-- --><\/p>\n<h3 class=\"chakra-heading css-145upk7\" id=\"eth\"><strong>Eth:<!-- --><\/strong><\/h3>\n<p><!-- --><strong>PPA<!-- --><\/strong>: <!-- --><a target=\"_blank\" rel=\"noopener\" class=\"chakra-link css-ug8vf0\" href=\"https:\/\/gavofyork.gitbooks.io\/turboethereum\/content\/chapter1.html\">https:\/\/gavofyork.gitbooks.io\/turboethereum\/content\/chapter1.html<!-- --><\/a><br \/>\n<!-- --><\/div>\n<p><br \/>\n<br \/><a href=\"https:\/\/blog.ethereum.org\/en\/2015\/10\/22\/security-alert-implementation-of-blockhash-instruction-in-c-and-go-clients-can-potentially-cause-consensus-issue-fixed-please-update\">Source link <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview: Flawed execution of BLOCKHASH may instigate a chain reorganization resulting in consensus complications Implicated configurations: All geth editions up to 1.1.3 and 1.2.2. All eth editions preceding 1.0.0. Probability: Low Impact Level: Medium Consequence: Medium Insights: Both C++ (eth) and Go (geth) clients feature a flawed execution of a rare scenario in the Ethereum<\/p>\n","protected":false},"author":3,"featured_media":8282,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[1634],"class_list":["post-9507","post","type-post","status-publish","format-standard","has-post-thumbnail","category-ethereum","tag-return-a-list-of-comma-separated-tags-from-this-title-security-alert-implementation-of-blockhash-instruction-in-c-and-go-clients-can-potentially-cause-consensus-issue-fixed-please-updat"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.3 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Critical Update: Addressing BLOCKHASH Instruction Concerns in C++ and Go Clients - WSJ-Crypto<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/wsj-crypto.com\/index.php\/2025\/03\/09\/critical-update-addressing-blockhash-instruction-concerns-in-c-and-go-clients\/\" \/>\n<meta property=\"og:locale\" content=\"it_IT\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Critical Update: Addressing BLOCKHASH Instruction Concerns in C++ and Go Clients - WSJ-Crypto\" \/>\n<meta property=\"og:description\" content=\"Overview: Flawed execution of BLOCKHASH may instigate a chain reorganization resulting in consensus complications Implicated configurations: All geth editions up to 1.1.3 and 1.2.2. 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