KEV Intelligence

Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-20349

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software Denial of Service

Cisco / Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · 9.16.1

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Severity
CVSS 8.6 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
0.9%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-20349 is an unauthenticated vulnerability affecting Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure.... A vulnerability in the Remote Access SSL VPN service for Cisco...

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.

Who is affected?

Cisco / Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software Denial of Service

A vulnerability in the Remote Access SSL VPN service for 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 insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device.

A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

Vendor Product Affected Status
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.4.22 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.2.10 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.4.57 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19.1.28 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.4.24 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.2.21 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.4.61 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19.1.31 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.4.29 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.2.22 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.4.62 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.4.34 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.3 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.4.67 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.4.70 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.4.40 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23.1 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22.1.1 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.4.71 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.3.4 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.4.47 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.3.7 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19.1.37 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.4.76 Affected
Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20.3.9 Affected
Published
11 Aug 2026
Exploitation Reported
11 Aug 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

edge cisa

CVE References

  • CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2026-20349
  • cisco-sa-asaftd-vpn-dos-dzv4mQFF sec.cloudapps.cisco.com · CVE Record https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurity...

Exploitation evidence

Why KEV Intelligence marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 11 Aug 2026

Independent exploitation attestation added to the KEV Intelligence record.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

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Source Added
CISA First 2026-08-11 18:59 UTC
CVE 2026-08-11 20:00 UTC
TheHackerNews 2026-08-12 06:15 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
0
User-Agents
0

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

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

EPSS

0.9%

Weaknesses

Improper Clearing of Heap Memory Before Release ('Heap Inspection') CWE-244

Recent mention · TheHackerNews

Cisco ASA and FTD Flaw Exploited in the Wild Can Trigger Remote DoS

Cisco has warned that a new vulnerability impacting Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software has been exploited in the wild. The high-severity flaw, tracked as CVE-2026-20349 (CVSS score: 8.6), is a case of...

Read full advisory

All Mentions

Recent mention · TheHackerNews

Cisco ASA and FTD Flaw Exploited in the Wild Can Trigger Remote DoS

TheHackerNews · 12 Aug 2026

Cisco has warned that a new vulnerability impacting Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software has been exploited in the wild. The high-severity flaw, tracked as CVE-2026-20349 (CVSS score: 8.6), is a case of insufficient error checking when processing HTTP requests that could allow an unauthenticated, remote attacker to trigger

Recent mention · Cisco Security Advisory

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability

Cisco Security Advisory · 11 Aug 2026

A vulnerability in the Remote Access SSL VPN service for 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 insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device. A successful exploit could allow the...

Timeline

From disclosure to observed exploitation

  1. KEV confirmed by TheHackerNews

    Exploitation attested by an external source

  2. Added to the KEV Intelligence watchlist

    Added to the KEV Intelligence curated list for closer monitoring

  3. KEV confirmed by CVE

    Exploitation attested by an external source

  4. Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  5. CVE published

    Vulnerability disclosed publicly

  6. CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-20349

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-20349",
  "confidence": "Confirmed",
  "cvss_score": 8.6,
  "cvss_estimated": false,
  "epss_score": 0.00874,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

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