CVE-2026-20249
HIGHDescription
A vulnerability in the certification authentication feature of Internet Key Exchange version 2 (IKEv2) for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly. This vulnerability is due to a logic error during the certificate authentication phase of the IKEv2 connection setup. An attacker could exploit this vulnerability by attempting to establish an IKEv2 VPN connection with a crafted certificate. A successful exploit could allow the attacker to cause the IKEv2 process to crash, causing a denial of service (DoS) condition.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Exploit Intelligence
EPSS data unavailable for this CVE.
References
Related Vulnerabilities
Other CWE-704 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-41646 | Critical | 9.8 | 52% | - | Fix |
| CVE-2017-5115 | High | 8.8 | 26% | - | Fix |
| CVE-2018-12453 | High | 7.5 | 24% | - | Fix |
| CVE-2017-3106 | High | 8.8 | 22% | - | - |
| CVE-2018-3843 | High | 8.8 | 22% | - | - |
| CVE-2018-5007 | High | 8.8 | 18% | - | - |
Common questions
How do I fix CVE-2026-20249?
No published fix for CVE-2026-20249 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
How severe is CVE-2026-20249?
CVE-2026-20249 has a CVSS v3 base score of 8.6, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-18.