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Vulnerabilities

Vulnerability · CVE-2020-3529

Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) Uncontrolled Resource Consumption

Published Apr 23, 2025 · catalog updated Apr 23, 2025 · Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)

Patch now

CVE-2020-3529 is in the CISA known-exploited catalog. Confirm Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
Unknown—
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
1.87%
Remediation
Remediation guidance
Affected products
vendor Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)

A vulnerability in the SSL VPN negotiation process for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to inefficient direct memory access (DMA) memory management during the negotiation phase of an SSL VPN connection. An attacker could exploit this vulnerability by sending a steady stream of crafted Datagram TLS (DTLS) traffic to an affected device. A successful exploit could allow

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD)version unspecified

How to fix CVE-2020-3529

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2020-3529 is in the CISA known-exploited catalog. Confirm Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

What should an analyst verify?

No weakness class is stored. EPSS 1.87%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Cisco security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 23, 2025 · VulnCheck KEV

    Detected

    A vulnerability in the SSL VPN negotiation process for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to inefficient direct memory access (DMA) memory management during the negotiation

  2. Apr 23, 2025 · CISA KEV

    Known exploited

    Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Sources

  • CVE.orgVulnerability recordCVE-2020-3529

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2020-3529

    30-day exploitation probability 1.9%

    first.org
  • VulnCheck KEVConfirmed exploitationCVE-2020-3529

    A vulnerability in the SSL VPN negotiation process for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a reload of an affected device, resulting in a denial of service (DoS

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.