{"id":64258,"date":"2025-08-23T07:06:20","date_gmt":"2025-08-23T07:06:20","guid":{"rendered":""},"modified":"2025-09-26T20:58:40","modified_gmt":"2025-09-27T02:58:40","slug":"cve-2025-20134-critical-denial-of-service-vulnerability-in-cisco-secure-firewall-software","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-20134-critical-denial-of-service-vulnerability-in-cisco-secure-firewall-software\/","title":{"rendered":"<strong>CVE-2025-20134: Critical Denial of Service Vulnerability in Cisco Secure Firewall Software<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>In this blog post, we will delve into the details of a significant cybersecurity vulnerability that has surfaced in the Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software. This vulnerability, designated as CVE-2025-20134, has the potential to cause grave system disruption and data leakage.<br \/>\nIt is of particular concern to organizations and entities that utilize <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-20217-denial-of-service-vulnerability-in-snort-3-detection-engine-of-cisco-secure-firewall-threat-defense-software\/\"  data-wpil-monitor-id=\"76924\">Cisco&#8217;s firewall<\/a> solutions for their network protection. This <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-33075-a-critical-windows-installer-vulnerability-that-leads-to-privilege-elevation\/\"  data-wpil-monitor-id=\"72383\">vulnerability could lead<\/a> to an unexpected system reload, rendering the device unresponsive and resulting in a Denial of Service (DoS), which can significantly impact an organization&#8217;s operations and service delivery.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-20134<br \/>\nSeverity: Critical, CVSS score of 8.6<br \/>\nAttack Vector: Network<br \/>\nPrivileges Required: None<br \/>\nUser Interaction: None<br \/>\nImpact: Denial of Service, <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-27055-memory-corruption-leads-to-potential-system-compromise-during-image-encoding\/\"  data-wpil-monitor-id=\"74292\">potential system compromise<\/a> or data leakage<\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-3785156173\" 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><a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-20133-remote-access-ssl-vpn-vulnerability-in-cisco-secure-firewall-asa-software-and-secure-ftd-software\/\"  data-wpil-monitor-id=\"76823\">Cisco Secure Firewall<\/a> Adaptive Security Appliance (ASA) Software | All versions prior to patch<br \/>\n<a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-20136-denial-of-service-vulnerability-in-cisco-secure-firewall-asa-and-ftd-software\/\"  data-wpil-monitor-id=\"76912\">Cisco Secure Firewall<\/a> Threat Defense (FTD) Software | All versions prior to patch<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-47982-improper-input-validation-vulnerability-in-windows-storage-vsp-driver-leading-to-privilege-escalation\/\"  data-wpil-monitor-id=\"75562\">vulnerability stems from improper<\/a> parsing of SSL\/TLS certificates by the Cisco Secure Firewall software. An attacker can exploit this <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-27061-memory-corruption-vulnerability-in-video-packet-parsing\/\"  data-wpil-monitor-id=\"74369\">vulnerability by crafting malicious DNS packets<\/a> that match a static Network Address Translation (NAT) rule with DNS inspection enabled. When these packets pass through the affected device, it triggers an <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-49746-improper-authorization-in-azure-machine-learning-leading-to-privilege-escalation\/\"  data-wpil-monitor-id=\"73306\">improper parsing process leading<\/a> to an unexpected system reboot, thus causing a DoS condition.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-1537847375\" 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 an attacker might craft a DNS <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-27058-memory-corruption-vulnerability-in-packet-data-processing\/\"  data-wpil-monitor-id=\"74730\">packet to exploit this vulnerability<\/a>:<\/p>\n<pre><code class=\"\" data-line=\"\"># Create a malicious DNS packet\ndns_packet = create_dns_packet()\n# Craft the packet to match a static NAT rule with DNS inspection enabled\ndns_packet.match_static_nat_rule(&#039;example.com&#039;)\n# Send the crafted packet through the targeted system\nsend_packet(dns_packet, &#039;target_system_ip&#039;)<\/code><\/pre>\n<p>Please note that this is a conceptual example and actual exploitation would require intricate knowledge of packet crafting and the target <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2022-43110-critical-unauthenticated-remote-system-configuration-vulnerability-in-voltronic-power-viewpower-powershield-netguard\/\"  data-wpil-monitor-id=\"83115\">system&#8217;s configuration<\/a>.<\/p>\n<p><strong>Mitigation Guidance<\/strong><\/p>\n<p>The recommended mitigation for this vulnerability is to apply the patch provided by the vendor. In situations where immediate patching is not possible, <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-31100-unrestricted-file-upload-leads-to-web-shell-deployment-in-mojoomla-school-management\/\"  data-wpil-monitor-id=\"84715\">deploying a Web<\/a> Application Firewall (WAF) or Intrusion Detection System (IDS) can serve as temporary mitigation by filtering out malicious DNS packets. However, these are not long-term solutions and organizations are strongly advised to apply the vendor patch as soon as feasible to ensure maximum protection against <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2024-7457-macos-authorization-model-exploit-leading-to-potential-mitm-attacks\/\"  data-wpil-monitor-id=\"79984\">potential exploits<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview In this blog post, we will delve into the details of a significant cybersecurity vulnerability that has surfaced in the Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software. This vulnerability, designated as CVE-2025-20134, has the potential to cause grave system disruption and data leakage. It is [&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":[96],"product":[],"attack_vector":[87],"asset_type":[],"severity":[],"exploit_status":[],"class_list":["post-64258","post","type-post","status-publish","format-standard","hentry","category-uncategorized","vendor-cisco","attack_vector-dos"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/64258","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=64258"}],"version-history":[{"count":12,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/64258\/revisions"}],"predecessor-version":[{"id":77500,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/64258\/revisions\/77500"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=64258"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=64258"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=64258"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=64258"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=64258"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=64258"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=64258"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=64258"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=64258"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}