Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1336 CNY

100%
Buy Us a Coffee

CVE-2026-20248— Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software TCP DNS Denial of Service Vulnerability

Quick assessment

Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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 ha

CVSS 6.8 · Medium
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-20248

Vulnerability Information

Shenlong is analyzing...

Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software TCP DNS Denial of Service Vulnerability
Source: CVE Program / CVE List V5
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
有符号至无符号转换错误
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1 -
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0 -

II. Public POCs for CVE-2026-20248

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-20248

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-20248 (1)

Same Patch Batch · Cisco · 2026-09-16 · 79 CVEs total

CVE-2026-20192 10.0 CRITICAL Cisco Identity Services Engine Hardening Release - Access Control Vulnerabilities
CVE-2026-76460 10.0 CRITICAL Cisco Identity Services Engine Authentication Bypass Vulnerability
CVE-2026-76423 10.0 CRITICAL Cisco ISE API Authentication Bypass Vulnerability
CVE-2026-20130 10.0 CRITICAL Cisco Identity Services Engine Hardening Release - Improper Neutralization Vulnerabilities
CVE-2026-20332 9.9 CRITICAL Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software
CVE-2026-20307 9.9 CRITICAL Cisco Identity Services Engine Remote Code Execution Vulnerability
CVE-2026-20234 9.9 CRITICAL Cisco Identity Services Engine Hardening Release - Insuffiencently Protected Credential Vu
CVE-2026-20324 9.9 CRITICAL Cisco Secure Firewall Management Center sftunnel Root Arbitrary Code Exectution Vulnerabil
CVE-2026-20325 9.9 CRITICAL Cisco Nexus Dashboard Software Security Hardening Release September 2026 - Improper Neutra
CVE-2026-20329 9.9 CRITICAL Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software
CVE-2026-20322 9.9 CRITICAL Cisco Nexus Dashboard Software Security Hardening Release September 2026 - Improper Access
CVE-2026-20330 9.9 CRITICAL Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software
CVE-2026-20242 9.8 CRITICAL Cisco Secure Firewall Management Center Software Java Deserialization Remote Code Executio
CVE-2026-20326 9.8 CRITICAL Cisco Nexus Dashboard Software Security Hardening Release September 2026 - Missing Authent
CVE-2026-20331 9.6 CRITICAL Cisco Secure Adaptive Security Appliance Software, Secure Firewall Threat Defense Software
CVE-2026-20306 9.1 CRITICAL Cisco Identity Services Engine Command Injection Vulnerability
CVE-2026-20211 9.1 CRITICAL Cisco Identity Services Engine Remote Code Execution Vulnerability
CVE-2026-20341 9.1 CRITICAL Cisco Secure Firewall Management Center Software sftunnel Deserialization Root Command Exe
CVE-2026-20176 9.1 CRITICAL Cisco Identity Services Engine Remote Code Execution Vulnerability
CVE-2026-20284 9.1 CRITICAL Cisco Identity Search Engine SXP REST API SQL Injection Vulnerability

Showing top 20 of 79 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Same vendor: Cisco
Same weakness: CWE-195

V. Comments for CVE-2026-20248

No comments yet

Leave a comment