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CVE-2026-20103

HIGHCVSS 8.6/10EPSS 0.35%

Last modified

CVE-2026-20103 is a high-severity vulnerability rated 8.6/10 on the CVSS scale. 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. EPSS estimates a 0.35% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
8.6/10

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

EPSS Probability
0.35%

27.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
CiscoAdaptive Security Appliance Software>= 9.12.1, < 9.16.4.85
CiscoAdaptive Security Appliance Software>= 9.17.1, < 9.18.4.66
CiscoAdaptive Security Appliance Software>= 9.19.1, < 9.20.4
CiscoAdaptive Security Appliance Software>= 9.22.1.1, < 9.22.2.4
CiscoAdaptive Security Appliance Software>= 9.23.1, < 9.23.1.7
CiscoFirepower Threat Defense Software>= 6.4.0, < 7.0.9
CiscoFirepower Threat Defense Software>= 7.1.0, < 7.2.11
CiscoFirepower Threat Defense Software>= 7.3.0, < 7.4.3
CiscoFirepower Threat Defense Software>= 7.6.0, < 7.6.4
CiscoFirepower Threat Defense Software>= 7.7.0, < 7.7.11

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is 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.
How severe is CVE-2026-20103?
CVE-2026-20103 has a CVSS score of 8.6/10 (HIGH severity). The EPSS model estimates a 0.35% probability of exploitation in the next 30 days.
How do I fix CVE-2026-20103?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-20103?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST