CVE-2026-20248 — MEDIUM (6.8)

Vulnerability Description

A vulnerability in the DNS over TCP implementation 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 TCP DNS response handler to unexpectedly restart, causing the device to reload. This vulnerability is due to a logic error when parsing a DNS query and tracking the size of the incoming buffers. An attacker could exploit this vulnerability by formatting a crafted reply to a DNS query sent from the targeted device. A successful exploit could allow the attacker to cause the device to reload, causing a denial of service (DoS) condition. Note: The attacker must be able to respond to DNS queries from the device, either by controlling the DNS service or through a machine-in-the-middle attack.

CVSS Score

6.8

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

CHANGED

Confidentiality

NONE

Integrity

NONE

Availability

HIGH

Related Weaknesses (CWE)

CWE-195

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/ci

FAQ

What is CVE-2026-20248?

CVE-2026-20248 is a vulnerability with a CVSS score of 6.8 (MEDIUM). A vulnerability in the DNS over TCP implementation of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenti...

How severe is CVE-2026-20248?

CVE-2026-20248 has been rated MEDIUM with a CVSS base score of 6.8/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-20248?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.