{"id":49003,"date":"2025-06-05T03:21:35","date_gmt":"2025-06-05T03:21:35","guid":{"rendered":""},"modified":"2025-08-31T06:32:23","modified_gmt":"2025-08-31T12:32:23","slug":"cve-2020-36846-critical-buffer-overflow-vulnerability-in-brotli-compression-library","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2020-36846-critical-buffer-overflow-vulnerability-in-brotli-compression-library\/","title":{"rendered":"<strong>CVE-2020-36846: Critical Buffer Overflow Vulnerability in Brotli Compression Library<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>The Common Vulnerabilities and Exposures (CVE) project has recently disclosed a critical security vulnerability, identified as CVE-2020-36846, that exists in versions of the IO::Compress::Brotli module prior to 0.007. The vulnerability stems from a buffer overflow condition in the embedded Brotli library, which can be exploited by an attacker to cause an application crash and potentially compromise the system. This vulnerability is of particular concern to organizations and individuals that rely on the Brotli compression library in their applications, as it poses a significant <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-48383-django-select2-vulnerability-risking-data-leakage-and-unauthorized-access\/\"  data-wpil-monitor-id=\"56092\">risk of data leakage<\/a> and system compromise if left unpatched.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2020-36846<br \/>\nSeverity: Critical (9.8 CVSS Score)<br \/>\nAttack Vector: Network<br \/>\nPrivileges Required: None<br \/>\nUser Interaction: None<br \/>\nImpact: Potential <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2023-42977-path-handling-vulnerability-that-risks-data-leakage-and-system-compromise\/\"  data-wpil-monitor-id=\"56962\">system compromise or data leakage<\/a><\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-2810395007\" 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: 700px;\">\r\n  <h2 style=\"margin-top: 0; font-size: 20px; font-weight: 600; display: flex; align-items: center;\">\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"display: inline-flex; align-items: center; margin-right: 8px;\">\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: 40px; height: 40px;\" \/>\r\n    <\/a>\r\n    A new way to communicate\r\n  <\/h2>\r\n\r\n  <p style=\"margin-bottom: 12px;\">\r\n    Ameeba Chat is built on encrypted identity, not personal profiles.\r\n  <\/p>\r\n\r\n  <p style=\"margin-bottom: 16px;\">\r\n    Message, call, share files, and coordinate with identities kept separate.\r\n  <\/p>\r\n\r\n  <ul style=\"list-style: none; padding-left: 0; margin-bottom: 20px;\">\r\n    <li>\u2022 Encrypted identity<\/li>\r\n    <li>\u2022 Ameeba Chat authenticates access<\/li>\r\n    <li>\u2022 Aliases and categories<\/li>\r\n    <li>\u2022 End-to-end encrypted chat, calls, and files<\/li>\r\n    <li>\u2022 Secure notes for sensitive information<\/li>\r\n  <\/ul>\r\n\r\n  <p style=\"font-style: italic; font-weight: 600; margin-bottom: 24px;\">\r\n    Private communication, rethought.\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: 6px; font-weight: 500;\">Download Ameeba Chat<\/a>\r\n    <a href=\"https:\/\/www.ameeba.com\/chat\" style=\"border: 1px solid #ffffff; color: #ffffff; padding: 10px 20px; text-decoration: none; border-radius: 6px; font-weight: 500;\">Learn More<\/a>\r\n  <\/div>\r\n<\/div>\r\n<\/div>\n<p>Product | Affected Versions<\/p>\n<p>IO::Compress::Brotli | <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-48481-critical-vulnerability-in-freescout-prior-to-version-1-8-180\/\"  data-wpil-monitor-id=\"57181\">Versions prior<\/a> to 0.007<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-31924-deserialization-of-untrusted-data-vulnerability-in-designthemes-crafts-arts\/\"  data-wpil-monitor-id=\"54927\">vulnerability exists due to inadequate handling of data<\/a> during the decompression process in the Brotli library. If an attacker can control the input length of a &#8220;one-shot&#8221; decompression request to a script, they can trigger a <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-5156-critical-buffer-overflow-vulnerability-in-h3c-gr-5400ax\/\"  data-wpil-monitor-id=\"54910\">buffer overflow<\/a> condition, causing the application to crash. This happens when copying over chunks of data larger than 2 GiB. In some scenarios, this could also lead to <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-48828-arbitrary-php-code-execution-in-vbulletin-via-template-conditionals\/\"  data-wpil-monitor-id=\"55735\">arbitrary code execution<\/a>, allowing the attacker to compromise the system.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-4117204630\" 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>Below is a conceptual example of how the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-45997-exploiting-file-upload-vulnerability-in-web-based-pharmacy-product-management-system\/\"  data-wpil-monitor-id=\"56963\">vulnerability might be exploited<\/a>. This is a pseudo-code representation of a malicious payload designed to trigger the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-5215-stack-based-buffer-overflow-vulnerability-in-d-link-dcs-5020l-1-01-b2\/\"  data-wpil-monitor-id=\"55057\">buffer overflow<\/a> condition:<\/p>\n<pre><code class=\"\" data-line=\"\">import brotli\ndef exploit(target):\npayload = b&quot;A&quot; * (2**31 + 1)  # More than 2 GiB of data.\ncompressed = brotli.compress(payload)\ntarget.decompress_one_shot(compressed)  # Trigger buffer overflow<\/code><\/pre>\n<p><strong>Mitigation<\/strong><\/p>\n<p>To mitigate this vulnerability, it is recommended to update your IO::Compress::Brotli module to version 0.007 or later. If updating is not possible, consider using the &#8220;streaming&#8221; API instead of the &#8220;one-shot&#8221; API, and impose chunk size limits on decompression requests. As a temporary measure, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can be used to detect and <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-8059-critical-privilege-escalation-vulnerability-in-b-blocks-wordpress-plugin\/\"  data-wpil-monitor-id=\"76400\">block attempts to exploit this vulnerability<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview The Common Vulnerabilities and Exposures (CVE) project has recently disclosed a critical security vulnerability, identified as CVE-2020-36846, that exists in versions of the IO::Compress::Brotli module prior to 0.007. The vulnerability stems from a buffer overflow condition in the embedded Brotli library, which can be exploited by an attacker to cause an application crash and [&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":[],"product":[],"attack_vector":[86,80],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-49003","post","type-post","status-publish","format-standard","hentry","category-uncategorized","attack_vector-buffer-overflow","attack_vector-rce"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/49003","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=49003"}],"version-history":[{"count":8,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/49003\/revisions"}],"predecessor-version":[{"id":68850,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/49003\/revisions\/68850"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=49003"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=49003"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=49003"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=49003"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=49003"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=49003"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=49003"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=49003"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=49003"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}