--- title: Exploitation of KnowledgeDeliver via ViewState... description: Mandiant investigated a late-2025 compromise of KnowledgeDeliver, a Japanese Learning Management System built on ASP.NET. The root cause was CVE-2026-5426: the... canonical: https://daily.dev/posts/exploitation-of-knowledgedeliver-via-viewstate-deserialization-vulnerability-cdxn7gdbl twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Exploitation of KnowledgeDeliver via ViewState Deserialization Vulnerability | daily.dev og:description: Mandiant investigated a late-2025 compromise of KnowledgeDeliver, a Japanese Learning Management System built on ASP.NET. The root cause was CVE-2026-5426: the... og:url: https://daily.dev/posts/exploitation-of-knowledgedeliver-via-viewstate-deserialization-vulnerability-cdxn7gdbl og:image: https://api.daily.dev/og/posts/CDxn7GDbl.png og:image:alt: Exploitation of KnowledgeDeliver via ViewState Deserialization Vulnerability og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Exploitation of KnowledgeDeliver via ViewState Deserialization Vulnerability **[Google Cloud](https://daily.dev/sources/gcp)** · 6 min read · 0 upvotes · 0 comments ## Summary Mandiant investigated a late-2025 compromise of KnowledgeDeliver, a Japanese Learning Management System built on ASP.NET. The root cause was CVE-2026-5426: the vendor shipped identical hardcoded ASP.NET machineKey values in all customer deployments, enabling unauthenticated RCE via crafted ViewState payloads. After gaining access, the threat actor deployed the BLUEBEAM (Godzilla) in-memory web shell inside the IIS worker process, modified JavaScript files to display fake security alerts, and ultimately infected end-user workstations with Cobalt Strike BEACON. Detection guidance covers Windows Event ID 1316, suspicious w3wp.exe child processes, file integrity monitoring, and anomalous concatenated User-Agent strings. Remediation requires immediately rotating machine keys to unique values per deployment. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Critical SharePoint RCE flaw exploited to steal machine keys](https://daily.dev/posts/critical-sharepoint-rce-flaw-exploited-to-steal-machine-keys-6nkweos4o) · BleepingComputer · 0 upvotes · 0 comments - [Unknown attackers exploit another critical SharePoint bug](https://daily.dev/posts/unknown-attackers-exploit-another-critical-sharepoint-bug-wlvkhutcz) · The Register · 0 upvotes · 0 comments - [Inside an Exposed Malware Delivery Lab: OPSEC Failures Behind a WebDAV Phishing Operation](https://daily.dev/posts/inside-an-exposed-malware-delivery-lab-opsec-failures-behind-a-webdav-phishing-operation-gbfnsi5pv) · Rapid7 Cybersecurity Blog · 0 upvotes · 0 comments - [BlueHammer Microsoft Defender Flaw Exploited in Ransomware Attacks](https://daily.dev/posts/bluehammer-microsoft-defender-flaw-exploited-in-ransomware-attacks-epvsqsotd) · Security Boulevard · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/exploitation-of-knowledgedeliver-via-viewstate-deserialization-vulnerability-cdxn7gdbl) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Exploitation of KnowledgeDeliver via ViewState Deserialization Vulnerability","url":"https://daily.dev/posts/exploitation-of-knowledgedeliver-via-viewstate-deserialization-vulnerability-cdxn7gdbl","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/exploitation-of-knowledgedeliver-via-viewstate-deserialization-vulnerability-cdxn7gdbl"},"datePublished":"2026-05-25T05:11:17.862Z","dateModified":"2026-08-24T06:57:39.213Z","description":"Mandiant investigated a late-2025 compromise of KnowledgeDeliver, a Japanese Learning Management System built on ASP.NET. The root cause was CVE-2026-5426: the...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/efb6ebdd31507ed6cdc6e0fe53ac3537?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/efb6ebdd31507ed6cdc6e0fe53ac3537?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Google Cloud","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Google Cloud","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/gcp","url":"https://daily.dev/sources/gcp"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/exploitation-of-knowledgedeliver-via-viewstate-deserialization-vulnerability-cdxn7gdbl","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"","timeRequired":"PT6M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Google Cloud","item":"https://daily.dev/sources/gcp"},{"@type":"ListItem","position":3,"name":"Exploitation of KnowledgeDeliver via ViewState Deserialization Vulnerability"}]} ```