CyberSecBulletin
CVE-2026-76418Exploited in the wildNVD status: Analyzed

Cisco Secure Firewall ASA Software and Cisco Secure FTD Software Unchecked Return Value to NULL Pointer Dereference

Published Updated By the CyberSecBulletin desk

CVE-2026-76418 is a high-severity unchecked return value to NULL pointer dereference vulnerability in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software from Cisco, with a CVSS 3.1 base score of 8.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Cisco Secure Firewall Adaptive Security Appliance (ASA) Software versions: 9.16.1; 9.16.1.28; 9.16.2, and others listed below. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on October 29, 2026, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Adaptive Security Appliance Software to 9.16.4.104 or 9.18.4.96 or 9.20.4.50 or 9.22.3.200, whichever matches your release line, or a later version.
  2. Update Secure Firewall Threat Defense to 7.0.11 or 7.2.13 or 7.4.9 or 7.7.14, whichever matches your release line, or a later version.
  3. CISA's 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.
  4. Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
  5. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
CiscoCisco Secure Firewall Adaptive Security Appliance (ASA) Software9.16.1; 9.16.1.28; 9.16.2; 9.16.2.3; 9.16.2.7; 9.16.2.11; 9.16.2.13; 9.16.2.14; and 32 more rangesNot stated
CiscoCisco Secure Firewall Threat Defense (FTD) Software7.0.0; 7.0.0.1; 7.0.1; 7.0.1.1; 7.0.2; 7.2.0; 7.0.2.1; 7.0.3; and 32 more rangesNot stated
CiscoAdaptive Security Appliance Softwarebefore 9.16.4.104; 9.18 up to, but not including, 9.18.4.96; 9.19 up to, but not including, 9.20.4.50; 9.22 up to, but not including, 9.22.3.200; 9.23 up to, but not including, 9.23.1.48; 9.24.1 up to, but not including, 9.24.1.27; 9.24.109.16.4.104, 9.18.4.96, 9.20.4.50, 9.22.3.200, 9.23.1.48, 9.24.1.27
CiscoSecure Firewall Threat Defensebefore 7.0.11; 7.2.0 up to, but not including, 7.2.13; 7.3.0 up to, but not including, 7.4.9; 7.6.0 through 7.6.7; 7.7.0 up to, but not including, 7.7.14; 10.0.0 up to, but not including, 10.0.3; 10.1.07.0.11, 7.2.13, 7.4.9, 7.7.14, 10.0.3

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H. Scored by CNA (cisco.com).

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Unchecked Return Value to NULL Pointer Dereference

The product does not check for an error after calling a function that can return with a NULL pointer if the function fails, which leads to a resultant NULL pointer dereference.

More Unchecked Return Value to NULL Pointer Dereference vulnerabilities (CWE-690)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: partial).
  3. Added to CISA's Known Exploited Vulnerabilities catalogue.
  4. Record last changed materially (score, affected products, status or references).
  5. Deadline for US federal agencies to remediate, set by CISA.

References

Third-party and government advisories

Our coverage

Other vulnerabilities in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software

All Cisco Secure Firewall Adaptive Security Appliance (ASA) Software vulnerabilities

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