{"id":64271,"date":"2025-08-23T20:10:15","date_gmt":"2025-08-23T20:10:15","guid":{"rendered":""},"modified":"2025-09-07T11:38:15","modified_gmt":"2025-09-07T17:38:15","slug":"cve-2025-20136-denial-of-service-vulnerability-in-cisco-secure-firewall-asa-and-ftd-software","status":"publish","type":"post","link":"https:\/\/www.ameeba.com\/blog\/cve-2025-20136-denial-of-service-vulnerability-in-cisco-secure-firewall-asa-and-ftd-software\/","title":{"rendered":"<strong>CVE-2025-20136: Denial of Service Vulnerability in Cisco Secure Firewall ASA and FTD Software<\/strong>"},"content":{"rendered":"<p><strong>Overview<\/strong><\/p>\n<p>A significant vulnerability has been discovered in the function that performs IPv4 and IPv6 Network Address Translation (NAT) DNS inspection for Cisco&#8217;s Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software. This vulnerability affects a broad range of businesses and institutions that rely on these products for their cybersecurity infrastructure. The exploit can lead to a denial of service (DoS) condition, which could <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-27055-memory-corruption-leads-to-potential-system-compromise-during-image-encoding\/\"  data-wpil-monitor-id=\"74302\">potentially compromise the system<\/a> or result in data leakage.<br \/>\nThe vulnerability, identified as CVE-2025-20136, is particularly concerning <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-31713-a-potential-privilege-escalation-vulnerability-due-to-command-injection\/\"  data-wpil-monitor-id=\"79476\">due to its potential<\/a> to cause severe disruption to crucial network services. The <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2024-7457-macos-authorization-model-exploit-leading-to-potential-mitm-attacks\/\"  data-wpil-monitor-id=\"79982\">exploit can lead<\/a> to an unexpected device reload, disrupting the normal operation of the device, and potentially impacting the security and integrity of the network.<\/p>\n<p><strong>Vulnerability Summary<\/strong><\/p>\n<p>CVE ID: CVE-2025-20136<br \/>\nSeverity: High (CVSS score 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-2025-27043-memory-corruption-vulnerability-leading-to-potential-system-compromise\/\"  data-wpil-monitor-id=\"75648\">potential system<\/a> compromise, and data leakage<\/p>\n<p><strong>Affected Products<\/strong><\/p><div id=\"ameeb-981407556\" 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=\"76820\">Cisco Secure Firewall ASA Software<\/a> | All versions with NAT44, NAT64, or NAT46 and DNS inspection enabled<br \/>\n<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=\"76923\">Cisco Secure Firewall<\/a> FTD Software | All versions with NAT44, NAT64, or NAT46 and DNS inspection enabled<\/p>\n<p><strong>How the Exploit Works<\/strong><\/p>\n<p>The <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-43275-critical-race-condition-vulnerability-in-macos\/\"  data-wpil-monitor-id=\"71651\">vulnerability is due to an infinite loop condition<\/a> that occurs when a Cisco Secure ASA or Cisco Secure FTD device processes DNS packets with DNS inspection enabled and the device is configured for NAT44, NAT64, or NAT46. 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=\"74368\">vulnerability by sending crafted DNS packets<\/a> that match a static NAT rule with DNS inspection enabled through an affected device. Successful exploitation could create an infinite loop, causing the device to reload and <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-20253-critical-vulnerability-in-ikev2-feature-of-cisco-software-could-lead-to-denial-of-service-dos-attack\/\"  data-wpil-monitor-id=\"76165\">leading to a Denial of Service<\/a> (DoS) condition.<\/p>\n<p><strong>Conceptual Example Code<\/strong><\/p><div id=\"ameeb-2151735141\" 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 exploit does not directly relate to a specific HTTP request or shell command, the conceptual implementation of this <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-27058-memory-corruption-vulnerability-in-packet-data-processing\/\"  data-wpil-monitor-id=\"74729\">vulnerability might involve sending a DNS packet<\/a> crafted to exploit the vulnerability. The code block below provides a conceptual example using a hypothetical DNS manipulation tool:<\/p>\n<pre><code class=\"\" data-line=\"\"># Using a hypothetical tool &#039;dns-exploit&#039;\ndns-exploit --target 192.168.1.1 --natrule &quot;static NAT rule&quot; --payload &quot;crafted DNS packet&quot;<\/code><\/pre>\n<p>In the above example, the attacker uses a hypothetical tool (`dns-exploit`) to send a crafted DNS packet that matches a static NAT rule with DNS inspection enabled, targeting the IP address of the <a href=\"https:\/\/www.ameeba.com\/blog\/cve-2025-30133-device-pairing-bypass-vulnerability-in-iroad-dashcam-fx2-devices\/\"  data-wpil-monitor-id=\"75647\">vulnerable device<\/a> (`192.168.1.1`).<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Overview A significant vulnerability has been discovered in the function that performs IPv4 and IPv6 Network Address Translation (NAT) DNS inspection for Cisco&#8217;s Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software. This vulnerability affects a broad range of businesses and institutions that rely on these products for their cybersecurity [&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-64271","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\/64271","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=64271"}],"version-history":[{"count":10,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/64271\/revisions"}],"predecessor-version":[{"id":72411,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/posts\/64271\/revisions\/72411"}],"wp:attachment":[{"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/media?parent=64271"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/categories?post=64271"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/tags?post=64271"},{"taxonomy":"vendor","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/vendor?post=64271"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/product?post=64271"},{"taxonomy":"attack_vector","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/attack_vector?post=64271"},{"taxonomy":"asset_type","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/asset_type?post=64271"},{"taxonomy":"severity","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/severity?post=64271"},{"taxonomy":"exploit_status","embeddable":true,"href":"https:\/\/www.ameeba.com\/blog\/wp-json\/wp\/v2\/exploit_status?post=64271"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}