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CVE-2025-20191

HIGHCVSS 7.4/10EPSS 0.20%

Last modified

CVE-2025-20191 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. 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. EPSS estimates a 0.20% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.4/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

EPSS Probability
0.20%

9.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2025-20191?
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.
How severe is CVE-2025-20191?
CVE-2025-20191 has a CVSS score of 7.4/10 (HIGH severity). The EPSS model estimates a 0.20% probability of exploitation in the next 30 days.
How do I fix CVE-2025-20191?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-20191?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST