CVE-2020-3338: A vulnerability in the Protocol Independent Multicast (PIM) feature for IPv6 networks (PIM6) of Cisco NX-OS Software could allow an unauthenticated, r...

Description

A vulnerability in the Protocol Independent Multicast (PIM) feature for IPv6 networks (PIM6) of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper error handling when processing inbound PIM6 packets. An attacker could exploit this vulnerability by sending multiple crafted PIM6 packets to an affected device. A successful exploit could allow the attacker to cause the PIM6 application to leak system memory. Over time, this memory leak could cause the PIM6 application to stop processing legitimate PIM6 traffic, leading to a DoS condition on the affected device.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.78%

75.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cisco	Nx-Os	All versions

References

Timeline

Published: Aug 27, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-3338?

A vulnerability in the Protocol Independent Multicast (PIM) feature for IPv6 networks (PIM6) of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper error handling when processing inbound PIM6 packets. An attacker could exploit this vulnerability by sending multiple crafted PIM6 packets to an affected device. A successful exploit could allow the attacker to cause the PIM6 application to leak system memory. Over time, this memory leak could cause the PIM6 application to stop processing legitimate PIM6 traffic, leading to a DoS condition on the affected device.

How severe is CVE-2020-3338?

CVE-2020-3338 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.78% probability of exploitation in the next 30 days.

How do I fix CVE-2020-3338?

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.