{"id":673,"date":"2026-04-22T10:51:56","date_gmt":"2026-04-22T10:51:56","guid":{"rendered":"https:\/\/thedigitalfortress.us\/?p=673"},"modified":"2026-04-22T10:51:56","modified_gmt":"2026-04-22T10:51:56","slug":"microsoft-patches-critical-asp-net-core-cve-2026-40372-privilege-escalation-bug","status":"publish","type":"post","link":"https:\/\/thedigitalfortress.us\/?p=673","title":{"rendered":"Microsoft Patches Critical ASP.NET Core CVE-2026-40372 Privilege Escalation Bug"},"content":{"rendered":"<div>\n<p><span class=\"p-author\"><i class=\"icon-font icon-user\">\ue804<\/i><span class=\"author\">Ravie Lakshmanan<\/span><i class=\"icon-font icon-calendar\">\ue802<\/i><span class=\"author\">Apr 22, 2026<\/span><\/span><span class=\"p-tags\">Vulnerability \/ Cryptography<\/span><\/p>\n<\/div>\n<div id=\"articlebody\">\n<div class=\"separator\" style=\"clear: both;\"><a href=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEiYMuDYXH3vQ6ycJCKfikptBR0jdQdnf-s36gDb0LYx3gvMwQOQLrt072KY5GZ0T2GRhyphenhyphenrfIg5qcCqjE0J_PtKQ1P409j_veWwKYoGsGssQcTotxI2-Dl8akDSyPif_j4LgFL3kWI6pvWKX5QBjsnIZIHdFzlAIRgxspuS4W0Ywe-Z63zmIyL7X39CG_3Ng\/s1700-e365\/dotnet.jpg\" style=\"display: block;  text-align: center; clear: left; float: left;\"><\/a><\/div>\n<p>Microsoft has released out-of-band updates to address a security vulnerability in ASP.NET Core that could allow an attacker to escalate privileges.<\/p>\n<p>The vulnerability, tracked as <strong>CVE-2026-40372<\/strong>, carries a CVSS score of 9.1 out of 10.0. It&#8217;s rated Important in severity. An anonymous researcher has been credited with discovering and reporting the flaw.<\/p>\n<p>\u00abImproper verification of cryptographic signature in ASP.NET Core allows an unauthorized attacker to elevate privileges over a network,\u00bb Microsoft <a href=\"https:\/\/msrc.microsoft.com\/update-guide\/vulnerability\/CVE-2026-40372\">said<\/a> in a Tuesday advisory. \u00abAn attacker who successfully exploited this vulnerability could gain SYSTEM privileges.\u00bb<\/p>\n<p>The tech giant said an attacker could abuse the vulnerability to disclose files and modify data, but emphasized that successful exploitation hinges on three prerequisites &#8211;<\/p>\n<ul>\n<li>The application uses Microsoft.AspNetCore.DataProtection 10.0.6 from NuGet (either directly or through a package that depends on it, such as Microsoft.AspNetCore.DataProtection.StackExchangeRedis).<\/li>\n<li>The NuGet copy of the library was actually loaded at runtime.<\/li>\n<li>The application runs on Linux, macOS, or another non-Windows operating system.<\/li>\n<\/ul>\n<div class=\"dog_two clear\">\n<div class=\"cf\"><a href=\"https:\/\/thehackernews.uk\/ai-agentic-guide-d-3\" rel=\"nofollow noopener sponsored\" target=\"_blank\"><img loading=\"lazy\" decoding=\"async\" class=\"lazyload\" alt=\"Cybersecurity\" src=\"https:\/\/blogger.googleusercontent.com\/img\/b\/R29vZ2xl\/AVvXsEgKLSgj9Smgyqpn4Kj-zAzWxJG1LUku8TpOERMxD6_hmMZQtXRFYXU-NA2ocnjrRafjkLtrxujKRuBstSZ4Il5z6hOu4oa7UM1FjkNoRQqrF5MWlShygYIqpnMGxHX2RHEBh9Y40x-p4PKn3cSlaWTEwKiVBDSoJgLPzR09dmp8HBffLlIqro73HVD30D00\/s728-e100\/nudge-d-3.jpg\" width=\"729\" height=\"91\"\/><\/a><\/div>\n<\/div>\n<p>The vulnerability has been addressed by Microsoft in <a href=\"https:\/\/dotnet.microsoft.com\/en-us\/download\/dotnet\/10.0\">ASP.NET Core version 10.0.7<\/a>.<\/p>\n<p>\u00abA regression in the Microsoft.AspNetCore.DataProtection 10.0.0-10.0.6 NuGet packages cause the managed authenticated encryptor to compute its HMAC validation tag over the wrong bytes of the payload and then discard the computed hash in some cases,\u00bb Microsoft <a href=\"https:\/\/github.com\/dotnet\/core\/blob\/main\/release-notes\/10.0\/10.0.7\/10.0.7.md\">explained<\/a> in its release notes.<\/p>\n<p>In such scenarios, an attacker could forge payloads that pass DataProtection&#8217;s authenticity checks, as wellas decrypt previously-protected payloads in authentication cookies, antiforgery tokens, and others.<\/p>\n<p>\u00abIf an attacker used forged payloads to authenticate as a privileged user during the vulnerable window, they may have induced the application to issue legitimately-signed tokens (session refresh, API key, password reset link, etc.) to themselves,\u00bb it added. \u00abThose tokens remain valid after upgrading to 10.0.7 unless the DataProtection key ring is rotated.\u00bb<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>\ue804Ravie Lakshmanan\ue802Apr 22, 2026Vulnerability \/ Cryptography Microsoft has released out-of-band updates to address a security vulnerability in ASP.NET Core that could allow an attacker to escalate privileges. The vulnerability, tracked&hellip;<\/p>\n","protected":false},"author":1,"featured_media":674,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[37,610,1350,58,1351,306,147,57,305],"class_list":["post-673","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-asp-net","tag-bug","tag-core","tag-critical","tag-cve202640372","tag-escalation","tag-microsoft","tag-patches","tag-privilege"],"_links":{"self":[{"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=\/wp\/v2\/posts\/673","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=673"}],"version-history":[{"count":0,"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=\/wp\/v2\/posts\/673\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=\/wp\/v2\/media\/674"}],"wp:attachment":[{"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=673"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=673"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thedigitalfortress.us\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=673"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}