CVE-2026-20082Network attack vector

Unauthenticated TCP service interruption via embryonic-limit mishandling

Published Mar 4, 2026 · Updated Mar 4, 2026

Denial of service in Cisco Secure Firewall ASA Software 9.20.4.14 allows remote attackers to block incoming TCP connections via SYN-flood traffic. The embryonic-connection limit logic mishandles new connections to management and data interfaces during a TCP SYN flood and incorrectly drops their SYN packets. Unauthenticated network access is sufficient, and successful exploitation blocks management, RAVPN, and other TCP-based services.

CVSS severity8.6
High
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco Secure Firewall ASA Software 9.20.4.14 allows remote attackers to block incoming TCP connections via SYN-flood traffic. The embryonic-connection limit logic mishandles new connections to management and data interfaces during a TCP SYN flood and incorrectly drops their SYN packets. Unauthenticated network access is sufficient, and successful exploitation blocks management, RAVPN, and other TCP-based services.

The record

CVE
CVE-2026-20082
Published
Mar 4, 2026
Updated
Mar 4, 2026
Vendor
ClamAV
Product
Cisco Adaptive Security Appliance (ASA) Software
Classifications
CWE-772, T1498.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=9.20.4.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Adaptive Security Appliance (ASA) Softwareversion=9.20.4.14

Published CVSS scores

8.6CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-772Missing Release of Resource after Effective Lifetime
T1498.001Direct Network Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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