CVE-2025-20191 Multiple Cisco Products Denial of Service Vulnerability
An unauthenticated adjacent attacker can cause a denial of service by sending crafted DHCPv6 packets to affected Cisco network devices.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-20191?
CVE-2025-20191 is a high-severity denial of service vulnerability in Cisco NX-OS Software, published on 7 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A vulnerability in the Switch Integrated Security Features (SISF) of Cisco IOS Software, Cisco IOS XE Software, Cisco NX-OS Software, and Cisco Wireless LAN Controller (WLC) AireOS Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to the incorrect handling of DHCPv6 packets. An attacker could exploit this vulnerability by sending a crafted DHCPv6 packet to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Weakness: CWE-805
Which versions are affected by CVE-2025-20191?
How do I fix CVE-2025-20191?
No fix has been published for CVE-2025-20191 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-20191 being exploited?
There is no known exploitation of CVE-2025-20191 in the wild and no public exploit code.
Sources
Also known as GHSA-vx24-6mq3-c5cq.