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Fencer Intel
high 8.6

CVE-2020-3572 json

Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software SSL/TLS Session Denial of Service Vulnerability

published 6y ago modified 2mo ago also EUVD-2020-24843

cvss
8.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

A vulnerability in the SSL/TLS session handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory leak when closing SSL/TLS connections in a specific state. An attacker could exploit this vulnerability by establishing several SSL/TLS sessions and ensuring they are closed under certain conditions. A successful exploit could allow the attacker to exhaust memory resources in the affected device, which would prevent it from processing new SSL/TLS connections, resulting in a DoS. Manual intervention is required to recover an affected device.

Patch / fix

  • cisco adaptive_security_appliance 9.6
  • cisco secure_firewall_threat_defense 6.3.0.6, 6.4.0.10, 6.6.1
  • cisco adaptive_security_appliance_software 9.8.4.26, 9.9.2.80, 9.10.1.44, 9.12.4.4, 9.13.1.13, 9.14.1.19

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
last yr.

Exploit prediction

1.80% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • Cisco Cisco Adaptive Security Appliance (ASA) Software

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-401 Missing Release of Memory after Effective Lifetime

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.