Adaptive Security Appliance Software
CVE-2026-20100
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate to Remote Access SSL VPN
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DeliverySend crafted HTTP packets to LUA interpreter
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ExploitTrigger unvalidated input processing
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ExecutionDevice reload caused
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ImpactDenial of service
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Buffer copy size validation
MITRE ATT&CK
1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Valid VPN authentication credentials required. Remote Access SSL VPN feature must be enabled on Cisco Secure Firewall ASA or FTD. Attacker must have legitimate VPN connection established to send HTTP packets to vulnerable LUA interpreter. |
| Impact | CVSS 7.7 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Exploitation requires authentication. Exploitable via remote/network. |
| Exploit ScenarioDerived | A remote attacker (requires authentication) could exploit this vulnerability to cause the device to reload, resulting in a DoS condition. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Cisco Secure Firewall ASA and FTD devices are vulnerable to a denial of service attack through the Remote Access SSL VPN feature, where authenticated attackers can trigger unvalidated input processing in the Lua interpreter to force device reloads. The vulnerability stems from insufficient input validation in the Lua interpreter and can be exploited by sending specially crafted HTTP packets over an existing VPN connection. No patch is currently available for this HIGH severity issue (CVSS 7.7).
Earlier versions of this analysis (1)
A vulnerability in the LUA interperter of the Remote Access SSL VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker with a valid VPN connection to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. [CVSS 7.7 HIGH]
RemediationAI
Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible. Restrict network access to the affected service where possible.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-120 (Classic Buffer Overflow). A vulnerability in the LUA interperter of the Remote Access SSL VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker with a valid VPN connection to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This does not affect the management or MUS interfaces. This vulnerability is due to trusting user input without validation in the LUA i
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Severity by source
AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
Primary rating from Vendor (cisco) · only source for this CVE.
CVSS VectorVendor: cisco
DescriptionCVE.org
A vulnerability in the LUA interperter of the Remote Access SSL VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker with a valid VPN connection to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This does not affect the management or MUS interfaces. This vulnerability is due to trusting user input without validation in the LUA interprerter. An attacker could exploit this vulnerability by sending crafted HTTP packets to the Remote Access SSL VPN server. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Executive ViewAI
A denial-of-service vulnerability in Cisco Secure Firewall VPN components could allow authenticated remote attackers to crash VPN gateways, disrupting remote worker connectivity and business operations. Organizations relying on SSL VPN for remote access face service interruption risk until mitigation or patching is completed.
Disable SSL VPN Remote Access feature if not operationally critical; restrict VPN access to specific user groups and IP ranges via access control lists; implement connection rate limiting and session timeouts on VPN gateways; enable detailed logging and alerting for VPN authentication events and device reload incidents; maintain hot-standby failover appliances to minimize DoS impact; monitor Cisco security advisories for patch releases daily.
Threat Intelligence Overview
NVD
CVE.org
EPSS
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)CVE.org
A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Th
A vulnerability in the web interface of the Cisco Adaptive Security Appliance (ASA) could allow an unauthenticated, remo
Multiple vulnerabilities in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Fir
Unauthenticated remote access to restricted VPN web server endpoints in Cisco Secure ASA and Firepower Threat Defense (F
A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Th
A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Th
Buffer overflow in the IKEv1 and IKEv2 implementations in Cisco ASA Software before 8.4(7.30), 8.7 before 8.7(1.18), 9.0
A vulnerability in the Secure Sockets Layer (SSL) VPN functionality of the Cisco Adaptive Security Appliance (ASA) Softw
Cisco ASA and FTD management and VPN web servers contain a vulnerability causing device reload through incomplete error
A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secu
Denial of service via crafted HTTP requests to the Remote Access SSL VPN service affects Cisco Secure Firewall ASA and F
Unauthenticated remote denial of service affecting Cisco Secure Firewall Adaptive Security Appliance (ASA) and Threat De
GitHub PoC
Exploit-DB