8.6

CVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability

CVSS: 8.6v3.1HighKEVAnalyzed
Published 11-08-2026Last modified 16-09-2026
Open JSON

Vulnerability summary

CVE-2026-20349 is a high (CVSS 8.6) Heap Inspection vulnerability in Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD). It is known to be exploited: CISA lists it, first on 11-08-2026. EPSS estimates a 1.01% chance of exploitation in the next 30 days, higher than 62.7% of scored vulnerabilities.

Overall risk
85/100
0100
Critical · default modelHow is this calculated?
CVSS score
8.6/10
010
High · v3.1 (CVE.org)
EPSS score
1.01%
0%100%
Low · -1.20 pp in 30 days
KEVListedCISA
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 11-08-2026
    PublishedVulnerability first disclosed.
  2. 11-08-2026
    Added to CISA KEVCisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability
  3. 14-08-2026
    CISA remediation dueApply mitigations per vendor instructions.
  4. 16-09-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

1.01%

Chance of exploitation in the next 30 days

Percentile

63%

Versus all other CVEs

30-day change

-1.20 pp

From 2.21% on 21-09-2026

21-09-202621-10-2026
EPSS score
1.01%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
11-08-2026
Federal due date
14-08-2026

CISA 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. sec.cloudapps.cisco.com/security/… nvd.nist.gov/vuln/detail/CVE-2026-20349

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Cisco4 products
  • adaptive_security_appliance_software9.16.1 | 9.16.1.28 | 9.16.2 | 9.16.2.3 | 9.16.2.7 | 9.16.2.11 | 9.16.2.13 | 9.16.2.14 | 9.16.3 | 9.16.3.3 | 9.16.3.14 | 9.16.3.15 | 9.16.3.19 | 9.16.3.23 | 9.16.4 | 9.16.4.9 | 9.16.4.14 | 9.16.4.19 | 9.16.4.27 | 9.16.4.38 | 9.16.4.39 | 9.16.4.42 | 9.16.4.48 | 9.16.4.55 | 9.16.4.57 | 9.16.4.61 | 9.16.4.62 | 9.16.4.67 | 9.16.4.70 | 9.16.4.71 | 9.16.4.76 | 9.16.4.82 | 9.16.4.84 | 9.16.4.85 | 9.16.4.89 | 9.16.4.92 | 9.18.1 | 9.18.1.3 | 9.18.2 | 9.18.2.5 | 9.18.2.7 | 9.18.2.8 | 9.18.3 | 9.18.3.39 | 9.18.3.46 | 9.18.3.53 | 9.18.3.55 | 9.18.3.56 | 9.18.4 | 9.18.4.5 | 9.18.4.8 | 9.18.4.22 | 9.18.4.24 | 9.18.4.29 | 9.18.4.34 | 9.18.4.40 | 9.18.4.47 | 9.18.4.50 | 9.18.4.52 | 9.18.4.53 | 9.18.4.57 | 9.18.4.66 | 9.18.4.67 | 9.18.4.68 | 9.18.4.71 | 9.18.4.76 | 9.18.4.82 | 9.18.4.90 | 9.18.4.135 | 9.19.1 | 9.19.1.5 | 9.19.1.9 | 9.19.1.12 | 9.19.1.18 | 9.19.1.22 | 9.19.1.24 | 9.19.1.27 | 9.19.1.28 | 9.19.1.31 | 9.19.1.37 | 9.19.1.38 | 9.19.1.42 | 9.20.1 | 9.20.1.5 | 9.20.2 | 9.20.2.10 | 9.20.2.21 | 9.20.2.22 | 9.20.3 | 9.20.3.4 | 9.20.3.7 | 9.20.3.9 | 9.20.3.10 | 9.20.3.13 | 9.20.3.16 | 9.20.3.20 | 9.20.4 | 9.20.4.7 | 9.20.4.10 | 9.20.4.14 | 9.20.4.19 | 9.20.4.22 | 9.20.4.28 | 9.20.4.30 | 9.20.4.34 | 9.20.4.46 | 9.22.1.1 | 9.22.1.2 | 9.22.1.3 | 9.22.1.6 | 9.22.2 | 9.22.2.4 | 9.22.2.9 | 9.22.2.13 | 9.22.2.14 | 9.22.2.20 | 9.22.2.32 | 9.22.3 | 9.22.3.5 | 9.23.1 | 9.23.1.3 | 9.23.1.7 | 9.23.1.13 | 9.23.1.19 | 9.23.1.22 | 9.23.1.26 | 9.23.1.32 | 9.23.1.195 | 9.24.1 | 9.24.1.5 | 9.24.1.9 | 9.24.1.11 | 9.24.1.155
  • cisco secure firewall adaptive security appliance (asa) software9.16.1 | 9.16.1.28 | 9.16.2 | 9.16.2.3 | 9.16.2.7 | 9.16.2.11 | 9.16.2.13 | 9.16.2.14 | 9.16.3.3 | 9.16.3 | 9.16.3.14 | 9.18.1 | 9.16.3.15 | 9.18.1.3 | 9.18.2 | 9.16.3.19 | 9.16.3.23 | 9.18.2.5 | 9.16.4 | 9.18.2.7 | 9.19.1 | 9.16.4.9 | 9.18.2.8 | 9.16.4.14 | 9.18.3 | 9.19.1.5 | 9.16.4.18 | 9.19.1.9 | 9.18.3.39 | 9.16.4.19 | 9.19.1.12 | 9.18.3.46 | 9.16.4.27 | 9.19.1.18 | 9.18.3.53 | 9.18.3.55 | 9.16.4.38 | 9.16.4.39 | 9.18.3.56 | 9.20.1 | 9.16.4.42 | 9.19.1.22 | 9.18.4 | 9.20.1.5 | 9.18.4.5 | 9.19.1.24 | 9.16.4.48 | 9.18.4.8 | 9.20.2 | 9.19.1.27 | 9.16.4.55 | 9.18.4.22 | 9.20.2.10 | 9.16.4.57 | 9.19.1.28 | 9.18.4.24 | 9.20.2.21 | 9.16.4.61 | 9.19.1.31 | 9.18.4.29 | 9.20.2.22 | 9.16.4.62 | 9.18.4.34 | 9.20.3 | 9.16.4.67 | 9.16.4.70 | 9.18.4.40 | 9.23.1 | 9.22.1.1 | 9.16.4.71 | 9.20.3.4 | 9.18.4.47 | 9.20.3.7 | 9.19.1.37 | 9.16.4.76 | 9.20.3.9 | 9.19.1.38 | 9.18.4.50 | 9.22.1.3 | 9.20.3.10 | 9.22.1.2 | 9.18.4.52 | 9.20.3.13 | 9.22.1.6 | 9.18.4.53 | 9.16.4.82 | 9.22.2 | 9.20.3.16 | 9.19.1.42 | 9.18.4.57 | 9.16.4.84 | 9.23.1.3 | 9.20.3.20 | 9.22.2.4 | 9.23.1.7 | 9.20.4 | 9.22.2.9 | 9.23.1.13 | 9.20.4.7 | 9.22.2.13 | 9.18.4.66 | 9.20.4.10 | 9.23.1.19 | 9.16.4.85 | 9.22.2.14 | 9.18.4.67 | 9.24.1 | 9.18.4.68 | 9.23.1.22 | 9.20.4.14 | 9.22.2.20 | 9.18.4.71 | 9.20.4.19 | 9.23.1.26 | 9.16.4.89 | 9.22.2.32 | 9.18.4.76 | 9.22.3 | 9.24.1.5 | 9.20.4.22 | 9.24.1.9 | 9.20.4.28 | 9.22.3.5 | 9.16.4.92 | 9.18.4.135 | 9.23.1.195 | 9.20.4.30 | 9.24.1.155 | 9.23.1.32 | 9.24.1.11 | 9.20.4.34 | 9.18.4.82
  • cisco secure firewall threat defense (ftd) software7.0.0 | 7.0.0.1 | 7.0.1 | 7.0.1.1 | 7.0.2 | 7.2.0 | 7.0.2.1 | 7.0.3 | 7.2.0.1 | 7.0.4 | 7.2.1 | 7.0.5 | 7.3.0 | 7.2.2 | 7.2.3 | 7.3.1 | 7.2.4 | 7.0.6 | 7.2.5 | 7.2.4.1 | 7.3.1.1 | 7.4.0 | 7.0.6.1 | 7.2.5.1 | 7.4.1 | 7.2.6 | 7.0.6.2 | 7.4.1.1 | 7.2.7 | 7.2.5.2 | 7.3.1.2 | 7.2.8 | 7.6.0 | 7.4.2 | 7.2.8.1 | 7.0.6.3 | 7.4.2.1 | 7.2.9 | 7.0.7 | 7.7.0 | 7.4.2.2 | 7.2.10 | 7.6.1 | 7.4.2.3 | 7.0.8 | 7.6.2 | 7.7.10 | 7.7.11 | 7.0.8.1 | 7.6.2.1 | 7.7.10.1 | 7.4.2.4 | 7.2.10.2 | 7.4.3 | 7.6.4 | 10.0.0 | 7.4.4 | 7.0.9 | 7.2.11 | 7.4.7 | 10.0.2
  • secure_firewall_threat_defense7.0.0 | 7.0.0.1 | 7.0.1 | 7.0.1.1 | 7.0.2 | 7.0.2.1 | 7.0.3 | 7.0.4 | 7.0.5 | 7.0.6 | 7.0.6.1 | 7.0.6.2 | 7.0.6.3 | 7.0.7 | 7.0.8 | 7.0.8.1 | 7.0.9 | 7.2.0 | 7.2.0.1 | 7.2.1 | 7.2.2 | 7.2.3 | 7.2.4 | 7.2.4.1 | 7.2.5 | 7.2.5.1 | 7.2.5.2 | 7.2.6 | 7.2.7 | 7.2.8 | 7.2.8.1 | 7.2.9 | 7.2.10 | 7.2.10.2 | 7.2.11 | 7.2.12 | 7.3.0 | 7.3.1 | 7.3.1.1 | 7.3.1.2 | 7.4.0 | 7.4.1 | 7.4.1.1 | 7.4.2 | 7.4.2.1 | 7.4.2.2 | 7.4.2.3 | 7.4.2.4 | 7.4.3 | 7.4.4 | 7.4.7 | 7.4.8 | 7.6.0 | 7.6.1 | 7.6.2 | 7.6.2.1 | 7.6.4 | 7.7.0 | 7.7.10 | 7.7.10.1 | 7.7.11 | 7.7.13 | 10.0.0 | 10.0.2

1 vendor · 4 products

References

2 links