CVE-2020-3479 Cisco IOS and IOS XE Software MP-BGP EVPN Denial of Service Vulnerability

Medium 6.1 Published 24 Sep 2020 Updated 13 Nov 2024

Remote attackers can crash Cisco IOS devices by sending malformed BGP EVPN update messages, causing a denial of service.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: None listed

What is CVE-2020-3479?

CVE-2020-3479 is a medium-severity denial of service vulnerability in Cisco Ios, published on 24 Sep 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

A vulnerability in the implementation of Multiprotocol Border Gateway Protocol (MP-BGP) for the Layer 2 VPN (L2VPN) Ethernet VPN (EVPN) address family in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of Border Gateway Protocol (BGP) update messages that contain crafted EVPN attributes. An attacker could exploit this vulnerability by sending BGP update messages with specific, malformed attributes to an affected device. A successful exploit could allow the attacker to cause an affected device to crash, resulting in a DoS condition.

Weakness: CWE-400, CWE-20

Which versions are affected by CVE-2020-3479?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2020-3479?

No fix has been published for CVE-2020-3479 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-2020-3479 being exploited?

There is no known exploitation of CVE-2020-3479 in the wild and no public exploit code.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-2x7q-2hq7-j42j.