CVEs / CVE-2026-76418
CVE-2026-76418: Cisco Secure Firewall ASA Software and Cisco Secure FTD Software Unchecked Return Value to NULL Pointer Dereference Vulnerability
- Known exploited in the CISA KEV catalog since 29 Oct 2026
- high 8.6 CVSS 3.1 (from the CNA)
- EPSS 0.91% chance of exploitation in the next 30 days, higher than 59% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Cisco Secure Firewall ASA Software and Cisco Secure FTD Software contains an unchecked return value to NULL pointer dereference vulnerability that could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.
Description
A vulnerability in the Remote Access SSL VPN service of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to logic errors when secondary authentication is configured on a tunnel group. An attacker could exploit this vulnerability by sending a crafted request when connecting to the SSL remote access VPN. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.1 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.1.28 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.2 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.2.3 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.2.7 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.2.11 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.2.13 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.2.14 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.3.3 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.3 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.3.14 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.18.1 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.3.15 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.18.1.3 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.18.2 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.3.19 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.3.23 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.18.2.5 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.4 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.18.2.7 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.19.1 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.4.9 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.18.2.8 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.4.14 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.18.3 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.19.1.5 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.4.18 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.19.1.9 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.18.3.39 | — |
| Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.16.4.19 | — |
Exploitation
| In CISA KEV since | 29 Oct 2026 |
|---|---|
| Due date for US federal agencies | 1 Nov 2026 |
| Used in ransomware campaigns | Unknown |
| Required action | Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. |
Severity
| CVSS 3.1 | 8.6 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:HScored by the CNA ([email protected]) |
|---|---|
| Weakness | CWE-690 |
On the Stackurity blog
References
- CVE-2026-76418 on NVD
- CVE-2026-76418 in the CISA KEV catalog
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-tunnel-dos-s6mgkb75 (cited by CISA)
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk (cited by CISA)
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk (cited by CISA)
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-tunnel-dos-s6mgkb75 Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76418 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.