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CVE-2026-20349

HIGH 8.6 KNOWN EXPLOITED

Published 2026-08-11 · Last modified 2026-08-12

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 · 61st percentile

● In CISA KEV (2026-08-11) ○ Public exploit / PoC

Impact if exploited

8.6CVSS 3.1 · HIGH

  • 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 & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-20349/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-20349/poc.json

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

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

Sources: NVD · CVE.org · EPSS