{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-20135 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-20135 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-20135 is a high-severity vulnerability in Cisco Secure Firewall Threat Defense (FTD) Software, published on 16 Sep 2026."},"fix_prompt":"Check this codebase for CVE-2026-20135 and fix it if it is affected.\n\nWhat it is: CVE-2026-20135 is a high-severity vulnerability in Cisco Secure Firewall Threat Defense (FTD) Software, published on 16 Sep 2026. \nExploitation: There is no known exploitation of CVE-2026-20135 in the wild and no public exploit code.\n\nAffected product: Cisco Secure Firewall Threat Defense (FTD) Software. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-20135/ (Markdown: https://insights.sbomify.com/CVE-2026-20135/index.md)","id":"CVE-2026-20135","markdown":"https://insights.sbomify.com/CVE-2026-20135/index.md","name":"CVE-2026-20135","record":{"aliases":["GHSA-6f7g-r5ww-w353"],"analysis":null,"analysis_generated_by":null,"assigner":"cisco","cpe":[],"cvss":{"score":8.6,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-415","name":"Double Free"}],"description":"A vulnerability in the TLS 1.3 implementation in Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition.\r\n\r\nThis vulnerability is due to improper buffer management during the TLS 1.3 connection. An attacker could exploit this vulnerability by sending a crafted TLS 1.3 packet to an affected system through a TLS 1.3-enabled listening socket. A successful exploit could allow the attacker to cause the LINA process to crash, which would cause the device to reload. The reload can happen before or after authentication of the connection.Note:\u0026nbsp;TLS 1.3 connections include both data traffic and user-management traffic.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":null,"headline":"Cisco Secure Firewall Threat Defense Software TLS 1.3 Denial of Service Vulnerability","id":"CVE-2026-20135","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":null,"year":"2026"},"n_packages":0,"n_references":1,"next":{"headline":"Cisco Identity Services Engine Authenticated Privilege Escalation Vulnerability","id":"CVE-2026-20136"},"packages":[],"prev":{"headline":"Cisco Catalyst SD-WAN Manager Exposure of Sensitive Information to an Unauthorized Actor","id":"CVE-2026-20133"},"products":["Cisco Secure Firewall Threat Defense (FTD) Software"],"published":"2026-09-16","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"yes","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-17","vendors":["Cisco"]},"summary":null,"url":"https://insights.sbomify.com/CVE-2026-20135/"}