Exploited vulnerabilities / CVE-2026-20349
Confirmed exploited · denial of service · Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD)CVE-2026-20349
Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) denial of service, confirmed exploited in the wild.
Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) contain a heap inspection vulnerability that could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.
| CISA's name for it | Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability |
|---|---|
| Vendor and product | Cisco · Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) |
| Type | denial of service · CWE-244 |
| Exploited | Confirmed by CISA listed 11 August 2026 |
| Likelihood | scored lower by EPSS, but already confirmed exploited, which outranks any prediction |
| Deadline | 14 August 2026 · already passed |
| Used in ransomware | Not reported |
| Advisories | sec.cloudapps.cisco.com ↗ · www.cisa.gov ↗ · www.cisa.gov ↗ · nvd.nist.gov ↗ |
Three steps, in this order
Apply the vendor's fix or mitigation; CISA lists only vulnerabilities seen exploited.
If you cannot patch now, restrict network access to the affected product.
Check for signs of compromise since the date it was added to the list.
| CISA's required action | Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. |
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Know before someone else finds it
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CVE-2026-20349 in short
Is CVE-2026-20349 being exploited?
Yes. CISA added CVE-2026-20349 to its Known Exploited Vulnerabilities catalogue on 11 August 2026, which it does only on evidence of exploitation in the wild.
What is the CISA deadline for CVE-2026-20349?
US federal agencies must remediate it by 14 August 2026. Everyone else should treat that date as the latest safe point to patch an internet-facing system.
How likely is CVE-2026-20349 to be exploited in the next 30 days?
FIRST's Exploit Prediction Scoring System gives it 1.0%, the 63rd percentile of every CVE it scores.
How do I fix CVE-2026-20349?
Apply the vendor's fix or mitigation; CISA lists only vulnerabilities seen exploited. If you cannot patch now, restrict network access to the affected product. Check for signs of compromise since the date it was added to the list.
Other Cisco vulnerabilities being exploited
| CVE | Product | Type | Listed |
|---|---|---|---|
| CVE-2026-20320 | BroadWorks | exploited vulnerability | 10 November 2026 |
| CVE-2026-76418 | Secure Firewall ASA Software and Cisco Secure FTD Software | denial of service | 29 October 2026 |
| CVE-2026-76519 | Secure Email Gateway | path traversal | 14 October 2026 |
| CVE-2026-76504 | Catalyst SD-WAN Manager | privilege escalation | 30 September 2026 |
| CVE-2026-76460 | Identity Services Engine | privilege escalation | 16 September 2026 |
| CVE-2026-76461 | Secure Email Gateway | SQL injection | 14 September 2026 |
Sources: CISA Known Exploited Vulnerabilities catalogue (released 10 November 2026) and FIRST EPSS. Page compiled automatically by SAK T.L.M, the threat-intelligence tool of SAK T.E.C, on 13 November 2026.