Cisco Secure Firewall ASA TCP Flood Denial of Service Vulnerability
CVE-2026-20082 is a denial-of-service vulnerability in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software related to the handling of embryonic connection limits. The flaw is caused by improper handling of new incoming TCP connections destined to management or data interfaces when the device is under a TCP SYN flood attack. A remote, unauthenticated attacker can exploit the issue by sending a crafted stream of traffic that causes the ASA to incorrectly drop incoming TCP SYN packets. As a result, legitimate inbound TCP connection establishment to the device can fail.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
13 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A denial-of-service vulnerability in Cisco Secure Firewall ASA Software involving improper handling of embryonic connection limits during TCP SYN flood conditions, allowing an unauthenticated remote attacker to disrupt incoming TCP connections (including management and VPN).
TCP flood denial of service vulnerability affecting Cisco Adaptive Security Appliance (ASA) software.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.