CVE-2025-20127
Aug. 15, 2025, 1:12 p.m.
7.7
High
Description
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.
Product(s) Impacted
| Vendor | Product | Versions |
|---|---|---|
| Cisco |
|
|
Weaknesses
Common security weaknesses mapped to this vulnerability.
CWE-404
Improper Resource Shutdown or Release
The product does not release or incorrectly releases a resource before it is made available for re-use.
*CPE(s)
Affected systems and software identified for this CVE.
| Type | Vendor | Product | Version | Update | Edition | Language | Software Edition | Target Software | Target Hardware | Other Information |
|---|---|---|---|---|---|---|---|---|---|---|
| a | cisco | secure_firewall_asa | / | / | / | / | / | / | / | / |
| a | cisco | secure_firewall_ftd | / | / | / | / | / | / | / | / |
| h | cisco | firepower_3100 | / | / | / | / | / | / | / | / |
| h | cisco | firepower_4200 | / | / | / | / | / | / | / | / |
Tags
CVSS Score
CVSS Data - 3.1
- Attack Vector: NETWORK
- Attack Complexity: LOW
- Privileges Required: LOW
- Scope: CHANGED
- Confidentiality Impact: NONE
- Integrity Impact: NONE
- Availability Impact: HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
Timeline
Published: Aug. 14, 2025, 5:15 p.m.
Last Modified: Aug. 15, 2025, 1:12 p.m.
Last Modified: Aug. 15, 2025, 1:12 p.m.
Status : Undergoing Analysis
CVE has been recently published to the CVE List and has been received by the NVD.
More infoSource
psirt@cisco.com
*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.