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CVE-2026-20349

HIGH 8.6 KNOWN EXPLOITED ALL-YEARS

Published 2026-08-11 · Last modified 2026-09-16 · cisco · NVD: Analyzed

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.

ACTIVELY EXPLOITED

Confirmed exploited in the wild — in CISA KEV since 2026-08-11. Patch or mitigate now.

Exploitation likelihood

1.0%chance of exploitation in 30 days · 63rd percentile

● In CISA KEV (2026-08-11)○ Catalogued PoC◆ SSVC: exploitation active, automatable yes

Impact if exploited

8.6CVSS 3.1 · HIGH · CNA

  • ConfidentialityNone
  • IntegrityNone
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

Search GitHub now — results may be empty or unverified.

Tracked sources are checked weekly for the full archive, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Affected

Vendors Cisco

Products Cisco Secure Firewall Adaptive Security Appliance (Asa) Software Cisco Secure Firewall Threat Defense (Ftd) Software Adaptive Security Appliance Software Secure Firewall Threat Defense

Weakness (CWE)

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

CVSS vector

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

References and research data (JSON)

Unverified PoC candidates

Catalogue matches for further research. These repositories have not been validated as working exploits.

1 candidate

Additional exploitation reports

Source-specific reports, separate from CISA KEV. Repeated observations from one source are not independent confirmations.

  • VulnCheck KEV · 2026-08-11T00:00:00Z

    Source guidance: 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.

    Source ransomware assessment: Unknown

    VulnCheck KEV · CVE-2026-20349 · Updated 2026-08-11T00:00:00Z
  • VulnCheck KEV · 2026-08-11T00:00:00ZVulnCheck KEV · CVE-2026-20349
    VulnCheck KEV · CVE-2026-20349
    VulnCheck KEV · CVE-2026-20349
  • VulnCheck KEV · 2026-08-12T00:00:00ZVulnCheck KEV · CVE-2026-20349
  • VulnCheck KEV · 2026-08-19T00:00:00ZVulnCheck KEV · CVE-2026-20349
  • VulnCheck KEV · 2026-08-21T00:00:00ZVulnCheck KEV · CVE-2026-20349
  • VulnCheck KEV · 2026-09-08T00:00:00ZVulnCheck KEV · CVE-2026-20349

Known Affected Software Configurations

VendorProductVersion range
CiscoAdaptive Security Appliance Software9.16.1
CiscoAdaptive Security Appliance Software9.16.1.28
CiscoAdaptive Security Appliance Software9.16.2
CiscoAdaptive Security Appliance Software9.16.2.3
CiscoAdaptive Security Appliance Software9.16.2.7
CiscoAdaptive Security Appliance Software9.16.2.11
CiscoAdaptive Security Appliance Software9.16.2.13
CiscoAdaptive Security Appliance Software9.16.2.14
CiscoAdaptive Security Appliance Software9.16.3
CiscoAdaptive Security Appliance Software9.16.3.3
CiscoAdaptive Security Appliance Software9.16.3.14
CiscoAdaptive Security Appliance Software9.16.3.15
CiscoAdaptive Security Appliance Software9.16.3.19
CiscoAdaptive Security Appliance Software9.16.3.23
CiscoAdaptive Security Appliance Software9.16.4
CiscoAdaptive Security Appliance Software9.16.4.9
CiscoAdaptive Security Appliance Software9.16.4.14
CiscoAdaptive Security Appliance Software9.16.4.19
CiscoAdaptive Security Appliance Software9.16.4.27
CiscoAdaptive Security Appliance Software9.16.4.38
CiscoAdaptive Security Appliance Software9.16.4.39
CiscoAdaptive Security Appliance Software9.16.4.42
CiscoAdaptive Security Appliance Software9.16.4.48
CiscoAdaptive Security Appliance Software9.16.4.55
CiscoAdaptive Security Appliance Software9.16.4.57
CiscoAdaptive Security Appliance Software9.16.4.61
CiscoAdaptive Security Appliance Software9.16.4.62
CiscoAdaptive Security Appliance Software9.16.4.67
CiscoAdaptive Security Appliance Software9.16.4.70
CiscoAdaptive Security Appliance Software9.16.4.71
CiscoAdaptive Security Appliance Software9.16.4.76
CiscoAdaptive Security Appliance Software9.16.4.82
CiscoAdaptive Security Appliance Software9.16.4.84
CiscoAdaptive Security Appliance Software9.16.4.85
CiscoAdaptive Security Appliance Software9.16.4.89
CiscoAdaptive Security Appliance Software9.16.4.92
CiscoAdaptive Security Appliance Software9.18.1
CiscoAdaptive Security Appliance Software9.18.1.3
CiscoAdaptive Security Appliance Software9.18.2
CiscoAdaptive Security Appliance Software9.18.2.5
CiscoAdaptive Security Appliance Software9.18.2.7
CiscoAdaptive Security Appliance Software9.18.2.8
CiscoAdaptive Security Appliance Software9.18.3
CiscoAdaptive Security Appliance Software9.18.3.39
CiscoAdaptive Security Appliance Software9.18.3.46
CiscoAdaptive Security Appliance Software9.18.3.53
CiscoAdaptive Security Appliance Software9.18.3.55
CiscoAdaptive Security Appliance Software9.18.3.56
CiscoAdaptive Security Appliance Software9.18.4
CiscoAdaptive Security Appliance Software9.18.4.5
CiscoAdaptive Security Appliance Software9.18.4.8
CiscoAdaptive Security Appliance Software9.18.4.22
CiscoAdaptive Security Appliance Software9.18.4.24
CiscoAdaptive Security Appliance Software9.18.4.29
CiscoAdaptive Security Appliance Software9.18.4.34
CiscoAdaptive Security Appliance Software9.18.4.40
CiscoAdaptive Security Appliance Software9.18.4.47
CiscoAdaptive Security Appliance Software9.18.4.50
CiscoAdaptive Security Appliance Software9.18.4.52
CiscoAdaptive Security Appliance Software9.18.4.53
CiscoAdaptive Security Appliance Software9.18.4.57
CiscoAdaptive Security Appliance Software9.18.4.66
CiscoAdaptive Security Appliance Software9.18.4.67
CiscoAdaptive Security Appliance Software9.18.4.68
CiscoAdaptive Security Appliance Software9.18.4.71
CiscoAdaptive Security Appliance Software9.18.4.76
CiscoAdaptive Security Appliance Software9.18.4.82
CiscoAdaptive Security Appliance Software9.18.4.90
CiscoAdaptive Security Appliance Software9.18.4.135
CiscoAdaptive Security Appliance Software9.19.1
CiscoAdaptive Security Appliance Software9.19.1.5
CiscoAdaptive Security Appliance Software9.19.1.9
CiscoAdaptive Security Appliance Software9.19.1.12
CiscoAdaptive Security Appliance Software9.19.1.18
CiscoAdaptive Security Appliance Software9.19.1.22
CiscoAdaptive Security Appliance Software9.19.1.24
CiscoAdaptive Security Appliance Software9.19.1.27
CiscoAdaptive Security Appliance Software9.19.1.28
CiscoAdaptive Security Appliance Software9.19.1.31
CiscoAdaptive Security Appliance Software9.19.1.37
CiscoAdaptive Security Appliance Software9.19.1.38
CiscoAdaptive Security Appliance Software9.19.1.42
CiscoAdaptive Security Appliance Software9.20.1
CiscoAdaptive Security Appliance Software9.20.1.5
CiscoAdaptive Security Appliance Software9.20.2
CiscoAdaptive Security Appliance Software9.20.2.10
CiscoAdaptive Security Appliance Software9.20.2.21
CiscoAdaptive Security Appliance Software9.20.2.22
CiscoAdaptive Security Appliance Software9.20.3
CiscoAdaptive Security Appliance Software9.20.3.4
CiscoAdaptive Security Appliance Software9.20.3.7
CiscoAdaptive Security Appliance Software9.20.3.9
CiscoAdaptive Security Appliance Software9.20.3.10
CiscoAdaptive Security Appliance Software9.20.3.13
CiscoAdaptive Security Appliance Software9.20.3.16
CiscoAdaptive Security Appliance Software9.20.3.20
CiscoAdaptive Security Appliance Software9.20.4
CiscoAdaptive Security Appliance Software9.20.4.7
CiscoAdaptive Security Appliance Software9.20.4.10
CiscoAdaptive Security Appliance Software9.20.4.14
CiscoAdaptive Security Appliance Software9.20.4.19
CiscoAdaptive Security Appliance Software9.20.4.22
CiscoAdaptive Security Appliance Software9.20.4.28
CiscoAdaptive Security Appliance Software9.20.4.30
CiscoAdaptive Security Appliance Software9.20.4.34
CiscoAdaptive Security Appliance Software9.20.4.46
CiscoAdaptive Security Appliance Software9.22.1.1
CiscoAdaptive Security Appliance Software9.22.1.2
CiscoAdaptive Security Appliance Software9.22.1.3
CiscoAdaptive Security Appliance Software9.22.1.6
CiscoAdaptive Security Appliance Software9.22.2
CiscoAdaptive Security Appliance Software9.22.2.4
CiscoAdaptive Security Appliance Software9.22.2.9
CiscoAdaptive Security Appliance Software9.22.2.13
CiscoAdaptive Security Appliance Software9.22.2.14
CiscoAdaptive Security Appliance Software9.22.2.20
CiscoAdaptive Security Appliance Software9.22.2.32
CiscoAdaptive Security Appliance Software9.22.3
CiscoAdaptive Security Appliance Software9.22.3.5
CiscoAdaptive Security Appliance Software9.23.1

Showing 120 of 197 configuration entries. Full list on NVD.

All CVSS metrics

  • HIGH 8.6 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
  • HIGH 8.6 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

References

Advisories

Technical & other

Sources: NVD · CVE.org · All sources and attribution · EPSS