CVE-2021-28505

Public Exploit
On affected Arista EOS platforms, if a VXLAN match rule exists in an IPv4 access-list that is applied to the ingress of an L2 or an L3 port/SVI, the VXLAN rule and subsequent ACL rules in that access list will ignore the specified IP protocol.

Description

On affected Arista EOS platforms, if a VXLAN match rule exists in an IPv4 access-list that is applied to the ingress of an L2 or an L3 port/SVI, the VXLAN rule and subsequent ACL rules in that access list will ignore the specified IP protocol.

Remediation

Solution:

  • The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Artista recommends customers move to the latest version of each release that contains all the fixes listed below. CVE-2021-28505 has been fixed in the following releases: 4.26.4M and later releases in the 4.26.x train 4.27.1F and later releases in the 4.27.x train

Workaround:

  • Replace "vxlan" IP protocol match with match on IP protocol "udp" and Layer 4 destination port for VxLAN encapsulated packets i.e 4789. < br/> If VXLAN L4 destination port number is not the default 4789 then use the configured L4 destination port number.

Categories

7.5
CVSS
Severity: High
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.20%
Vendor Advisory arista.com
Affected: Arista Networks EOS
Published at:
Updated at:

References

Link Tags
https://www.arista.com/en/support/advisories-notices/security-advisories/15267-security-advisory-0073 vendor advisory exploit

Frequently Asked Questions

What is the severity of CVE-2021-28505?
CVE-2021-28505 has been scored as a high severity vulnerability.
How to fix CVE-2021-28505?
To fix CVE-2021-28505: The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Artista recommends customers move to the latest version of each release that contains all the fixes listed below. CVE-2021-28505 has been fixed in the following releases: 4.26.4M and later releases in the 4.26.x train 4.27.1F and later releases in the 4.27.x train
Is CVE-2021-28505 being actively exploited in the wild?
It is possible that CVE-2021-28505 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-28505?
CVE-2021-28505 affects Arista Networks EOS.
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