- 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.
- Source
- psirt@cisco.com
- NVD status
- Analyzed
- Products
- firepower_threat_defense, adaptive_security_appliance_software
CVSS 3.1
- Type
- Primary
- Base score
- 7.7
- Impact score
- 4
- Exploitability score
- 3.1
- Vector string
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
- Severity
- HIGH
- psirt@cisco.com
- CWE-404
- Hype score
- Not currently trending
The @NSACyber and other agencies released guidance today on the exploitation of a serious @Cisco SD-WAN bug CVE-2025-20127. Cisco also has updates and guidance available. https://t.co/TgLWQQuFpn
@DecipherSec
26 Feb 2026
197 Impressions
0 Retweets
3 Likes
1 Bookmark
0 Replies
0 Quotes
CVE-2025-20127 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 Thr… https://t.co/HBqLwgbQvA
@CVEnew
15 Aug 2025
214 Impressions
0 Retweets
1 Like
0 Bookmarks
0 Replies
0 Quotes
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