Adaptive Security Appliance Software
CVE-2025-20127
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2021 - Security Misconfiguration
ASVS 5.0
V15 - Secure Coding and Architecture Resource release
|
| Impact | CVSS score of 7.7 (HIGH). Attack characteristics: network attack vector, low complexity, low privileges required, no user interaction not required. EPSS exploitation probability: 0.19%. |
| Exploit ScenarioDerived | This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system. |
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Alert meAnalysisAIv1 – Mar 28, 2026
A vulnerability in the TLS 1.3 implementation for a specific cipher for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software for. Rated high severity (CVSS 7.7), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.
Affects your stack
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Technical ContextAI · show details
This vulnerability is classified under CWE-404. A vulnerability in the TLS 1.3 implementation for a specific cipher for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software for Cisco Firepower 3100 and 4200 Series devices could allow an authenticated, remote attacker to consume resources that are associated with incoming TLS 1.3 connections, which eventually could cause the device to stop accepting any new SSL/TLS or VPN requests. This vulnerability is due to the implementation of the TLS 1.3 Cipher TLS_CHACHA20_POLY1305_SHA256. An attacker could exploit this vulnerability by sending a large number of TLS 1.3 connections with the specific TLS 1.3 Cipher TLS_CHACHA20_POLY1305_SHA256. A successful exploit could allow the attacker to cause a denial of service (DoS) condition where no new incoming encrypted connections are accepted. The device must be reloaded to clear this condition. Note: These incoming TLS 1.3 connections include both data traffic and user-management traffic. After the device is in the vulnerable state, no new encrypted connections can be accepted. Affected products include: Cisco Firepower Threat Defense, Cisco Adaptive Security Appliance Software.
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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 TLS 1.3 implementation for a specific cipher for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software for Cisco Firepower 3100 and 4200 Series devices could allow an authenticated, remote attacker to consume resources that are associated with incoming TLS 1.3 connections, which eventually could cause the device to stop accepting any new SSL/TLS or VPN requests.
This vulnerability is due to the implementation of the TLS 1.3 Cipher TLS_CHACHA20_POLY1305_SHA256. An attacker could exploit this vulnerability by sending a large number of TLS 1.3 connections with the specific TLS 1.3 Cipher TLS_CHACHA20_POLY1305_SHA256. A successful exploit could allow the attacker to cause a denial of service (DoS) condition where no new incoming encrypted connections are accepted. The device must be reloaded to clear this condition. Note: These incoming TLS 1.3 connections include both data traffic and user-management traffic. After the device is in the vulnerable state, no new encrypted connections can be accepted.
Executive ViewAI
CVE-2025-20127 presents notable security risk rated CVSS 7.7. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and consider compensating controls in the interim.
Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.
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
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
A vulnerability in the remote access VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower
GitHub PoC
Exploit-DB