Resource exhaustion in Cisco Adaptive Security Appliance Software
CVE-2026-20103
A vulnerability in the Remote Access SSL VPN functionality of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to exhaust device memory resulting in a denial of service (DoS) condition to new Remote Access SSL VPN connections. This does not affect the management interface, though it may become temporarily unresponsive. This vulnerability is due to trusting user input without validation. An attacker could exploit this vulnerability by sending crafted packets to the Remote Access SSL VPN server. A successful exploit could allow the attacker to cause the device web interface to stop responding, resulting in a DoS condition.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (27.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 27.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000
Affected products
- Cisco Adaptive Security Appliance Software
- Cisco Secure Firewall Adaptive Security Appliance (Asa) Software — versions 9.12.4.48, 9.12.4.50, 9.12.4.52
- Cisco Secure Firewall Threat Defense (Ftd) Software — versions 6.4.0.16, 6.4.0.17, 6.4.0.18
- Cisco Firepower Threat Defense Software
- Cisco Secure Firewall Threat Defense
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-20103?
- CVE-2026-20103 is a high-severity vulnerability in Cisco Adaptive Security Appliance Software, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 8.6/10. Published 2026-03-04.
- How severe is CVE-2026-20103?
- High severity. CVSS v3 base score is 8.6 out of 10.