{"id":49460,"date":"2025-06-07T06:44:55","date_gmt":"2025-06-07T06:44:55","guid":{"rendered":""},"modified":"2025-06-09T23:26:26","modified_gmt":"2025-06-10T05:26:26","slug":"cve-2021-47670-linux-kernel-vulnerability-threatens-system-compromise","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2021-47670-linux-kernel-vulnerability-threatens-system-compromise\/","title":{"rendered":"<strong>CVE-2021-47670: Linux Kernel Vulnerability Threatens System Compromise<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>In our digital era, the security of the Linux kernel is of paramount importance due to its widespread usage by businesses and individuals alike. A newly discovered vulnerability, known as CVE-2021-47670, threatens this security. This <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-46458-critical-cross-site-request-forgery-csrf-vulnerability-leading-to-sql-injection-in-occupancyplan\/\"  data-wpil-monitor-id=\"55485\">vulnerability could potentially lead<\/a> to system compromise or data leakage, making it a significant concern for all Linux users.<br \/>\nThis blog post aims to provide an in-depth understanding of CVE-2021-47670, its potential impact, and how it can be mitigated. The vulnerability primarily affects the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-21879-the-linux-kernel-btrfs-use-after-free-vulnerability\/\"  data-wpil-monitor-id=\"56543\">Linux kernel and arises from a use-after-free<\/a> bug in the peak_usb module.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2021-47670<br \/>\nSeverity: High (7.8 CVSS score)<br \/>\nAttack Vector: Local<br \/>\nPrivileges Required: Low<br \/>\nUser Interaction: None<br \/>\nImpact: Potential system compromise or <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-48383-django-select2-vulnerability-risking-data-leakage-and-unauthorized-access\/\"  data-wpil-monitor-id=\"56125\">data leakage<\/a><\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-2441068788\" class=\"ameeb-content-2 ameeb-entity-placement\"><div style=\"border-left: 4px solid #555; padding-left: 20px; margin: 48px 0; font-family: Roboto, sans-serif; color: #ffffff; line-height: 1.6; max-width: 720px;\">\r\n  <h2 style=\"margin-top: 0; font-size: 22px; font-weight: 600; display: flex; align-items: center; letter-spacing: -0.02em;\">\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"display: inline-flex; align-items: center; margin-right: 10px;\">\r\n      <img decoding=\"async\" src=\"https:\/\/www.ameeba.com\/blog\/wp-content\/uploads\/2025\/10\/Best-App-icon-Ameeba.png\" alt=\"Ameeba Chat Icon\" style=\"width: 42px; height: 42px;\" \/>\r\n    <\/a>\r\n    Share secrets securely\r\n  <\/h2>\r\n\r\n  <p style=\"margin-bottom: 14px; color: #d1d5db;\">\r\n    Ameeba is private infrastructure for communication and sensitive work built on encrypted identity instead of exposed corporate identity systems.\r\n  <\/p>\r\n\r\n  <p style=\"margin-bottom: 18px; color: #a1a1aa;\">\r\n    Passwords, credentials, confidential files, screenshots, internal discussions, sensitive AI context, and private coordination should not become exposed across ordinary communication platforms.\r\n  <\/p>\r\n\r\n  <ul style=\"list-style: none; padding-left: 0; margin-bottom: 24px; color: #e4e4e7;\">\r\n    <li style=\"margin-bottom: 8px;\">\u2022 Encrypted identity<\/li>\r\n    <li style=\"margin-bottom: 8px;\">\u2022 Private Spaces for organizations and teams<\/li>\r\n    <li style=\"margin-bottom: 8px;\">\u2022 End-to-end encrypted chat, calls, files, and notes<\/li>\r\n    <li style=\"margin-bottom: 8px;\">\u2022 Sensitive AI work and protected collaboration<\/li>\r\n    <li>\u2022 Built for information that cannot leak<\/li>\r\n  <\/ul>\r\n\r\n  <p style=\"font-style: italic; font-weight: 600; margin-bottom: 24px; color: #ffffff;\">\r\n    Our mission is to secure human work alongside AI.\r\n  <\/p>\r\n\r\n  <div style=\"display: flex; flex-wrap: wrap; gap: 12px;\">\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\/download\" style=\"background-color: #ffffff; color: #000000; padding: 10px 20px; text-decoration: none; border-radius: 8px; font-weight: 500;\">\r\n      Download Ameeba\r\n    <\/a>\r\n\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"border: 1px solid #ffffff; color: #ffffff; padding: 10px 20px; text-decoration: none; border-radius: 8px; font-weight: 500;\">\r\n      Learn More\r\n    <\/a>\r\n  <\/div>\r\n<\/div><\/div>\n<p>Product | Affected Versions<\/p>\n<p><a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-21893-critical-linux-kernel-vulnerability-in-key-put-function\/\"  data-wpil-monitor-id=\"56816\">Linux Kernel<\/a> | Up to 5.13.19<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-5228-critical-buffer-overflow-vulnerability-in-d-link-di-8100\/\"  data-wpil-monitor-id=\"55696\">vulnerability arises from the unsafe dereferencing of the socket buffer<\/a> (skb) after calling peak_usb_netif_rx_ni(skb). Specifically, the can_frame cf, which aliases the skb memory is accessed after the peak_usb_netif_rx_ni(). This leads to a use-after-free condition, which can then be exploited to <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-48828-arbitrary-php-code-execution-in-vbulletin-via-template-conditionals\/\"  data-wpil-monitor-id=\"55729\">execute arbitrary code<\/a> or cause a denial of service.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-3940851652\" class=\"ameeb-content ameeb-entity-placement\"><div class=\"poptin-embedded\" data-id=\"f6b387694f681\"><\/div>\r\n\r\n\r\n\r\n\r\n\r\n<\/div>\n<p>While the exact exploit code may differ based on the specific circumstances, the following is a conceptual example in pseudocode of how the vulnerability might be exploited:<\/p>\n<pre><code class=\"\" data-line=\"\">\/\/ Allocate socket buffer\nstruct sk_buff *skb = alloc_skb(...);\n\/\/ Fill the buffer with data\n...\n\/\/ Call peak_usb_netif_rx_ni(), which frees the socket buffer\npeak_usb_netif_rx_ni(skb);\n\/\/ Access the freed buffer, leading to a use-after-free condition\nstruct can_frame *cf = (struct can_frame *)skb-&gt;data;<\/code><\/pre>\n<p>Note: This example is for illustrative purposes only and does not represent a working exploit.<\/p>\n<p><strong>Mitigation Guidance<\/strong><\/p>\n<p>The recommended mitigation for this vulnerability is to apply the vendor-provided patch. This will resolve the vulnerability by reordering the lines involved in the issue. However, as a temporary mitigation, using a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) can also help to detect and prevent exploitation attempts.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview In our digital era, the security of the Linux kernel is of paramount importance due to its widespread usage by businesses and individuals alike. A newly discovered vulnerability, known as CVE-2021-47670, threatens this security. This vulnerability could potentially lead to system compromise or data leakage, making it a significant concern for all Linux users. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"footnotes":""},"categories":[1],"tags":[],"vendor":[88],"product":[95],"attack_vector":[87],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-49460","post","type-post","status-publish","format-standard","hentry","category-uncategorized","vendor-linux","product-linux-kernel","attack_vector-dos"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/49460","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/comments?post=49460"}],"version-history":[{"count":6,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/49460\/revisions"}],"predecessor-version":[{"id":50734,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/49460\/revisions\/50734"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=49460"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=49460"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=49460"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=49460"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=49460"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=49460"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=49460"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=49460"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=49460"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}