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CVE-2020-3165

Cisco NX-OS Software Border Gateway Protocol MD5 Authentication Bypass Vulnerability

8.2 High

A vulnerability in the implementation of Border Gateway Protocol (BGP) Message Digest 5 (MD5) authentication in Cisco NX-OS Software could allow an unauthenticated, remote attacker to bypass MD5 authentication and establish a BGP connection with the device. The vulnerability occurs because the BGP MD5 authentication is bypassed if the peer does not have MD5 authentication configured, the NX-OS device does have BGP MD5 authentication configured, and the NX-OS BGP virtual routing and forwarding (VRF) name is configured to be greater than 19 characters. An attacker could exploit this vulnerability by attempting to establish a BGP session with the NX-OS peer. A successful exploit could allow the attacker to establish a BGP session with the NX-OS device without MD5 authentication. The Cisco implementation of the BGP protocol accepts incoming BGP traffic only from explicitly configured peers. To exploit this vulnerability, an attacker must send the malicious packets over a TCP connection that appears to come from a trusted BGP peer. To do so, the attacker must obtain information about the BGP peers in the affected system’s trusted network.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
High
Availability
None

Exploit likelihood

1.56%Up 1.0 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used8.2

Cisco NX-OS Software Border Gateway Protocol MD5 Authentication Bypass Vulnerability

A vulnerability in the implementation of Border Gateway Protocol (BGP) Message Digest 5 (MD5) authentication in Cisco NX-OS Software could allow an unauthenticated, remote attacker to bypass MD5 authentication and establish a BGP connection with the device. The vulnerability occurs because the BGP MD5 authentication is bypassed if the peer does not have MD5 authentication configured, the NX-OS device does have BGP MD5 authentication configured, and the NX-OS BGP virtual routing and forwarding (VRF) name is configured to be greater than 19 characters. An attacker could exploit this vulnerability by attempting to establish a BGP session with the NX-OS peer. A successful exploit could allow the attacker to establish a BGP session with the NX-OS device without MD5 authentication. The Cisco implementation of the BGP protocol accepts incoming BGP traffic only from explicitly configured peers. To exploit this vulnerability, an attacker must send the malicious packets over a TCP connection that appears to come from a trusted BGP peer. To do so, the attacker must obtain information about the BGP peers in the affected system’s trusted network.

Record
CVE-2020-3165
CVSS 3.0
8.2 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
Weakness
CWE-798
Updated
2026-11-02
EUVDEUVD-2020-244368.2

A vulnerability in the implementation of Border Gateway Protocol (BGP) Message Digest 5 (MD5) authentication in Cisco NX-OS Software could allow an unauthenticated, remote attacker to bypass MD5 authentication and establish a BGP connection with the device. The vulnerability occurs because the BGP MD5 authentication is bypassed if the peer does not have MD5 authentication configured, the NX-OS device does have BGP MD5 authentication configured, and the NX-OS BGP virtual routing and forwarding (VRF) name is configured to be greater than 19 characters. An attacker could exploit this vulnerability by attempting to establish a BGP session with the NX-OS peer. A successful exploit could allow the attacker to establish a BGP session with the NX-OS device without MD5 authentication. The Cisco implementation of the BGP protocol accepts incoming BGP traffic only from explicitly configured peers. To exploit this vulnerability, an attacker must send the malicious packets over a TCP connection that appears to come from a trusted BGP peer. To do so, the attacker must obtain information about the BGP peers in the affected system’s trusted network.

Record
EUVD-2020-24436
CVSS 3.0
8.2 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-ggpf-8579-4r92No score

A vulnerability in the implementation of Border Gateway Protocol (BGP) Message Digest 5 (MD5)...

A vulnerability in the implementation of Border Gateway Protocol (BGP) Message Digest 5 (MD5) authentication in Cisco NX-OS Software could allow an unauthenticated, remote attacker to bypass MD5 authentication and establish a BGP connection with the device. The vulnerability occurs because the BGP MD5 authentication is bypassed if the peer does not have MD5 authentication configured, the NX-OS device does have BGP MD5 authentication configured, and the NX-OS BGP virtual routing and forwarding (VRF) name is configured to be greater than 19 characters. An attacker could exploit this vulnerability by attempting to establish a BGP session with the NX-OS peer. A successful exploit could allow the attacker to establish a BGP session with the NX-OS device without MD5 authentication. The Cisco implementation of the BGP protocol accepts incoming BGP traffic only from explicitly configured peers. To exploit this vulnerability, an attacker must send the malicious packets over a TCP connection that appears to come from a trusted BGP peer. To do so, the attacker must obtain information about the BGP peers in the affected system’s trusted network.

Record
GHSA-ggpf-8579-4r92
Updated
2026-11-02
NVD8.2

A vulnerability in the implementation of Border Gateway Protocol (BGP) Message Digest 5 (MD5) authentication in Cisco NX-OS Software could allow an unauthenticated, remote attacker to bypass MD5 authentication and establish a BGP connection with the device. The vulnerability occurs because the BGP MD5 authentication is bypassed if the peer does not have MD5 authentication configured, the NX-OS device does have BGP MD5 authentication configured, and the NX-OS BGP virtual routing and forwarding (VRF) name is configured to be greater than 19 characters. An attacker could exploit this vulnerability by attempting to establish a BGP session with the NX-OS peer. A successful exploit could allow the attacker to establish a BGP session with the NX-OS device without MD5 authentication. The Cisco implementation of the BGP protocol accepts incoming BGP traffic only from explicitly configured peers. To exploit this vulnerability, an attacker must send the malicious packets over a TCP connection that appears to come from a trusted BGP peer. To do so, the attacker must obtain information about the BGP peers in the affected system’s trusted network.

Record
CVE-2020-3165
CVSS 3.1
8.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
CVSS 3.0
8.2 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:N/I:P/A:N
Weakness
CWE-798
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
facts
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-3165 is a high vulnerability (CVSS 8.2) in Cisco Nx-os Software, published February 26, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.56%, the 75th percentile. No source names a fixed version.

References

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