CVE-2021-28511: This advisory documents the impact of an internally found vulnerability in Arista EOS for security ACL bypass. The impact of this vulnerability is that the security ACL drop rule might be bypassed if a NAT ACL rule filter with permit action matches t ...
First published: Fri Aug 05 2022(Updated: )
This advisory documents the impact of an internally found vulnerability in Arista EOS for security ACL bypass. The impact of this vulnerability is that the security ACL drop rule might be bypassed if a NAT ACL rule filter with permit action matches the packet flow. This could allow a host with an IP address in a range that matches the range allowed by a NAT ACL and a range denied by a Security ACL to be forwarded incorrectly as it should have been denied by the Security ACL. This can enable an ACL bypass.
Credit: psirt@arista.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Arista EOS | <=4.24.9 | |
| Arista EOS | >=4.25.0<=4.25.8 | |
| Arista EOS | >=4.26.0<=4.26.5 | |
| Arista EOS | >=4.27.0<=4.27.3 | |
| Arista 7050cx3-32s | ||
| Arista 7050cx3m-32s | ||
| Arista 7050sx3-48c8 | ||
| Arista 7050sx3-48yc | ||
| Arista 7050sx3-48yc12 | ||
| Arista 7050sx3-48yc8 | ||
| Arista 7050sx3-96yc8 | ||
| Arista 7050tx3-48c8 | ||
| Arista 720xp-24y6 | ||
| Arista 720xp-24zy4 | ||
| Arista 720xp-48y6 | ||
| Arista 720xp-48zc2 | ||
| Arista 720xp-96zc2 | ||
| Arista 7300x3-32c | ||
| Arista 7300x3-48yc4 |
Remedy
The recommended resolution is to upgrade to a remediated software version at your earliest convenience. The fixed versions for the currently supported release trains are as follows: 4.24.10 and later releases in the 4.24.x train 4.25.9 and later releases in the 4.25.x train 4.26.6 and later releases in the 4.26.x train 4.27.4 and later releases in the 4.27.x train 4.28.0 and later releases in the 4.28.x train
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Reference Links
Frequently Asked Questions
What is the vulnerability ID?
The vulnerability ID is CVE-2021-28511.
What is the impact of the vulnerability?
The impact of the vulnerability is that the security ACL drop rule might be bypassed if a NAT ACL rule filter with permit action matches the packet flow.
Which software is affected by the vulnerability?
Arista EOS versions up to 4.24.9, 4.25.0 to 4.25.8, 4.26.0 to 4.26.5, and 4.27.0 to 4.27.3 are affected by the vulnerability.
What is the severity of the vulnerability?
The severity of the vulnerability is medium with a CVSS score of 6.5.
How can I fix the vulnerability?
To fix the vulnerability, update Arista EOS to a version that is not affected.
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- collector/mitre-cve
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- agent/severity
- agent/title
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- agent/last-modified-date
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- agent/references
- agent/tags
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- agent/event
- vendor/arista
- canonical/arista eos
- version/arista eos/4.24.9
- version/arista eos/4.25.0
- version/arista eos/4.25.8
- version/arista eos/4.26.0
- version/arista eos/4.26.5
- version/arista eos/4.27.0
- version/arista eos/4.27.3
- canonical/arista 7050cx3-32s
- canonical/arista 7050cx3m-32s
- canonical/arista 7050sx3-48c8
- canonical/arista 7050sx3-48yc
- canonical/arista 7050sx3-48yc12
- canonical/arista 7050sx3-48yc8
- canonical/arista 7050sx3-96yc8
- canonical/arista 7050tx3-48c8
- canonical/arista 720xp-24y6
- canonical/arista 720xp-24zy4
- canonical/arista 720xp-48y6
- canonical/arista 720xp-48zc2
- canonical/arista 720xp-96zc2
- canonical/arista 7300x3-32c
- canonical/arista 7300x3-48yc4