{ "document": { "acknowledgments": [ { "summary": "This vulnerability was found during the resolution of a Cisco Technical Assistance Center (TAC) support case." } ], "category": "csaf_security_advisory", "csaf_version": "2.0", "notes": [ { "category": "summary", "title": "Summary", "text": "A vulnerability in the handling of the embryonic connection limits in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause incoming TCP SYN packets to be dropped incorrectly.\r\n\r\nThis vulnerability is due to improper handling of new, incoming TCP connections that are destined to management or data interfaces when the device is under a TCP SYN flood attack. An attacker could exploit this vulnerability by sending a crafted stream of traffic to an affected device. A successful exploit could allow the attacker to prevent all incoming TCP connections to the device from being established, including remote management access, Remote Access VPN (RAVPN) connections, and all network protocols that are TCP-based. This results in a denial of service (DoS) condition for affected features.\r\n\r\nCisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.\r\n\r\n\r\n\r\nThis advisory is part of the March 2026 release of the Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2026 Semiannual Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication [\"https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75736\"]." }, { "category": "general", "title": "Vulnerable Products", "text": "This vulnerability affects only Cisco Secure Firewall ASA Software Release 9.20.4.14, regardless of device configuration. The fixed software release for this vulnerability is Cisco Secure Firewall ASA Software Release 9.20.4.19.\r\n\r\nFor more information, see the Fixed Software [\"#fs\"] section of this advisory." }, { "category": "general", "title": "Products Confirmed Not Vulnerable", "text": "Only products listed in the Vulnerable Products [\"#vp\"] section of this advisory are known to be affected by this vulnerability.\r\n\r\nCisco has confirmed that this vulnerability does not affect Cisco Secure Firewall Management Center (FMC) Software or Cisco Secure Firewall Threat Defense (FTD) Software." }, { "category": "general", "title": "Workarounds", "text": "There are no workarounds that address this vulnerability." }, { "category": "general", "title": "Fixed Software", "text": "Cisco considers any workarounds and mitigations (if applicable) to be temporary solutions until an upgrade to a fixed software release is available. To fully remediate this vulnerability and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.\r\n Fixed Releases\r\nCustomers are advised to upgrade to an appropriate fixed software release [\"https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes\"] as indicated in the following table:\r\n Cisco Secure Firewall ASA Software Release First Fixed Release 9.20.4.14 9.20.4.19\r\nThe Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.\r\n Additional Resources\r\nFor help determining the best Cisco Secure Firewall ASA, Secure FMC, or Secure FTD Software release, see the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.\r\n\r\nCisco Secure Firewall ASA Compatibility [\"https://www.cisco.com/c/en/us/td/docs/security/asa/compatibility/asamatrx.html\"]\r\nCisco Secure Firewall ASA Upgrade Guide [\"https://www.cisco.com/c/en/us/td/docs/security/asa/upgrade/asa-upgrade/planning.html\"]\r\nCisco Secure Firewall Threat Defense Compatibility Guide [\"https://www.cisco.com/c/en/us/td/docs/security/secure-firewall/compatibility/threat-defense-compatibility.html\"]" }, { "category": "general", "title": "Vulnerability Policy", "text": "To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy [\"http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html\"]. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco." }, { "category": "general", "title": "Exploitation and Public Announcements", "text": "The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory." }, { "category": "general", "title": "Source", "text": "This vulnerability was found during the resolution of a Cisco Technical Assistance Center (TAC) support case." }, { "category": "legal_disclaimer", "title": "Legal Disclaimer", "text": "SOFTWARE DOWNLOADS AND TECHNICAL SUPPORT\r\n\r\nThe Cisco Support and Downloads [\"https://www.cisco.com/c/en/us/support/index.html\"] page on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool. Please note that customers may download only software that was procured from Cisco directly or through a Cisco authorized reseller or partner and for which the license is still valid.\r\n\r\nCustomers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco Technical Assistance Center (TAC) [\"https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html\"]. Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.\r\n\r\nWhen considering software upgrades [\"https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes\"], customers are advised to regularly consult the advisories [\"https://www.cisco.com/go/psirt\"] for the relevant Cisco products to determine exposure and a complete upgrade solution. In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) [\"https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html\"] or their contracted maintenance providers.\r\n LEGAL DISCLAIMER DETAILS\r\n\r\nCISCO DOES NOT MAKE ANY EXPRESS OR IMPLIED GUARANTEES OR WARRANTIES OF ANY KIND, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. WITHOUT LIMITING THE GENERALITY OF THE FOREGOING, CISCO DOES NOT GUARANTEE THE ACCURACY OR COMPLETENESS OF THIS INFORMATION. THIS DOCUMENT IS PROVIDED ON AN \"AS IS\" BASIS. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.\r\n\r\nCopies or summaries of the information contained in this Security Advisory may lack important information or contain factual errors. Customers are advised to visit the Cisco Security Advisories [\"https://www.cisco.com/go/psirt\"] page for the most recent version of this Security Advisory. The Cisco Product Security Incident Response Team (PSIRT) assesses only the affected and fixed release information that is documented in this advisory. See the Cisco Security Vulnerability Policy [\"https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes\"] for more information." } ], "publisher": { "category": "vendor", "contact_details": "psirt@cisco.com", "issuing_authority": "Cisco PSIRT", "name": "Cisco", "namespace": "https://wwww.cisco.com" }, "references": [ { "category": "self", "summary": "Cisco Secure Firewall Adaptive Security Appliance Software TCP Flood Denial of Service Vulnerability", "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-dos-FCvLD6vR" }, { "category": "external", "summary": "Cisco Event Response: March 2026 Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication", "url": "https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75736" }, { "category": "external", "summary": "Cisco Security Vulnerability Policy", "url": "https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html" }, { "category": "external", "summary": "fixed software release", "url": "https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes" }, { "category": "external", "summary": "Cisco Secure Firewall ASA Compatibility", "url": "https://www.cisco.com/c/en/us/td/docs/security/asa/compatibility/asamatrx.html" }, { "category": "external", "summary": "Cisco Secure Firewall ASA Upgrade Guide", "url": "https://www.cisco.com/c/en/us/td/docs/security/asa/upgrade/asa-upgrade/planning.html" }, { "category": "external", "summary": "Cisco Secure Firewall Threat Defense Compatibility Guide", "url": "https://www.cisco.com/c/en/us/td/docs/security/secure-firewall/compatibility/threat-defense-compatibility.html" }, { "category": "external", "summary": "Security Vulnerability Policy", "url": "http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html" }, { "category": "external", "summary": "Cisco Support and Downloads", "url": "https://www.cisco.com/c/en/us/support/index.html" }, { "category": "external", "summary": "Cisco Technical Assistance Center (TAC)", "url": "https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html" }, { "category": "external", "summary": "the advisories", "url": "https://www.cisco.com/go/psirt" } ], "title": "Cisco Secure Firewall Adaptive Security Appliance Software TCP Flood Denial of Service Vulnerability", "tracking": { "current_release_date": "2026-03-04T16:00:00+00:00", "generator": { "date": "2026-08-08T01:32:16+00:00", "engine": { "name": "TVCE" } }, "id": "cisco-sa-asa-dos-FCvLD6vR", "initial_release_date": "2026-03-04T16:00:00+00:00", "revision_history": [ { "date": "2026-03-04T16:08:06+00:00", "number": "1.0.0", "summary": "Initial public release." } ], "status": "final", "version": "1.0.0" } }, "product_tree": { "branches": [ { "name": "Cisco", "category": "vendor", "branches": [ { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software", "category": "product_family", "branches": [ { "name": "9.20", "category": "product_version", "branches": [ { "name": "9.20.4.14", "category": "service_pack", "product": { "name": "9.20.4.14", "product_id": "CSAFPID-306830" } } ] } ] }, { "name": "Cisco Firepower 2100 Series", "category": "product_name", "product": { "name": "Cisco Firepower 2100 Series", "product_id": "CSAFPID-277392" } }, { "name": "Cisco Firepower 1000 Series", "category": "product_name", "product": { "name": "Cisco Firepower 1000 Series", "product_id": "CSAFPID-277393" } }, { "name": "Cisco 3000 Series Industrial Security Appliances (ISA)", "category": "product_name", "product": { "name": "Cisco 3000 Series Industrial Security Appliances (ISA)", "product_id": "CSAFPID-277438" } }, { "name": "Cisco Firepower 9000 Series", "category": "product_name", "product": { "name": "Cisco Firepower 9000 Series", "product_id": "CSAFPID-277440" } }, { "name": "Cisco Firepower 4100 Series", "category": "product_name", "product": { "name": "Cisco Firepower 4100 Series", "product_id": "CSAFPID-277441" } }, { "name": "Cisco Adaptive Security Virtual Appliance (ASAv)", "category": "product_name", "product": { "name": "Cisco Adaptive Security Virtual Appliance (ASAv)", "product_id": "CSAFPID-277511" } }, { "name": "Cisco Secure Firewall 3100 Series", "category": "product_name", "product": { "name": "Cisco Secure Firewall 3100 Series", "product_id": "CSAFPID-286865" } }, { "name": "Cisco Secure Firewall 4200 Series", "category": "product_name", "product": { "name": "Cisco Secure Firewall 4200 Series", "product_id": "CSAFPID-300754" } } ] } ], "relationships": [ { "category": "installed_on", "full_product_name": { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.4.14 when installed on Cisco Firepower 2100 Series", "product_id": "CSAFPID-306830:277392" }, "product_reference": "CSAFPID-306830", "relates_to_product_reference": "CSAFPID-277392" }, { "category": "installed_on", "full_product_name": { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.4.14 when installed on Cisco Firepower 1000 Series", "product_id": "CSAFPID-306830:277393" }, "product_reference": "CSAFPID-306830", "relates_to_product_reference": "CSAFPID-277393" }, { "category": "installed_on", "full_product_name": { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.4.14 when installed on Cisco 3000 Series Industrial Security Appliances (ISA)", "product_id": "CSAFPID-306830:277438" }, "product_reference": "CSAFPID-306830", "relates_to_product_reference": "CSAFPID-277438" }, { "category": "installed_on", "full_product_name": { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.4.14 when installed on Cisco Firepower 9000 Series", "product_id": "CSAFPID-306830:277440" }, "product_reference": "CSAFPID-306830", "relates_to_product_reference": "CSAFPID-277440" }, { "category": "installed_on", "full_product_name": { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.4.14 when installed on Cisco Firepower 4100 Series", "product_id": "CSAFPID-306830:277441" }, "product_reference": "CSAFPID-306830", "relates_to_product_reference": "CSAFPID-277441" }, { "category": "installed_on", "full_product_name": { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.4.14 when installed on Cisco Adaptive Security Virtual Appliance (ASAv)", "product_id": "CSAFPID-306830:277511" }, "product_reference": "CSAFPID-306830", "relates_to_product_reference": "CSAFPID-277511" }, { "category": "installed_on", "full_product_name": { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.4.14 when installed on Cisco Secure Firewall 3100 Series", "product_id": "CSAFPID-306830:286865" }, "product_reference": "CSAFPID-306830", "relates_to_product_reference": "CSAFPID-286865" }, { "category": "installed_on", "full_product_name": { "name": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.4.14 when installed on Cisco Secure Firewall 4200 Series", "product_id": "CSAFPID-306830:300754" }, "product_reference": "CSAFPID-306830", "relates_to_product_reference": "CSAFPID-300754" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-20082", "ids": [ { "system_name": "Cisco Bug ID", "text": "CSCwr58661" } ], "notes": [ { "category": "other", "title": "Affected Product Comprehensiveness", "text": "Complete." } ], "product_status": { "known_affected": [ "CSAFPID-306830:277392", "CSAFPID-306830:277393", "CSAFPID-306830:277438", "CSAFPID-306830:277440", "CSAFPID-306830:277441", "CSAFPID-306830:277511", "CSAFPID-306830:286865", "CSAFPID-306830:300754" ] }, "release_date": "2026-03-04T16:00:00+00:00", "remediations": [ { "category": "vendor_fix", "details": "Cisco has released software updates that address this vulnerability.", "product_ids": [ "CSAFPID-306830:277392", "CSAFPID-306830:277393", "CSAFPID-306830:277438", "CSAFPID-306830:277440", "CSAFPID-306830:277441", "CSAFPID-306830:277511", "CSAFPID-306830:286865", "CSAFPID-306830:300754" ], "url": "https://software.cisco.com" } ], "scores": [ { "cvss_v3": { "baseScore": 8.6, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H", "version": "3.1" }, "products": [ "CSAFPID-306830:277392", "CSAFPID-306830:277393", "CSAFPID-306830:277438", "CSAFPID-306830:277440", "CSAFPID-306830:277441", "CSAFPID-306830:277511", "CSAFPID-306830:286865", "CSAFPID-306830:300754" ] } ], "title": "Cisco Secure Firewall Adaptive Security Appliance (ASA) Software TCP SYN flood Denial of Service Vulnerability" } ] }