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 ...

MEDIUM
6.5
CVSS Score
Published: August 5, 2022 at 04:47 PM UTC
Updated: June 17, 2026 at 03:46 AM UTC
17 products affected across 2 vendorsEos7050Cx3M-32S7050Tx3-48C8

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 4.24.94.25.0 ≤ v ≤ 4.25.84.26.0 ≤ v ≤ 4.26.54.27.0 ≤ v ≤ 4.27.3
arista-7050cx3-32s (environment) · arista-7050cx3m-32s (environment) · arista-7050sx3-48c8 (environment) · arista-7050sx3-48yc (environment) · arista-7050sx3-48yc12 (environment) · arista-7050sx3-48yc8 (environment) · arista-7050sx3-96yc8 (environment) · arista-7050tx3-48c8 (environment) · arista-720xp-24y6 (environment) · arista-720xp-24zy4 (environment) · arista-720xp-48y6 (environment) · arista-720xp-48zc2 (environment) · arista-720xp-96zc2 (environment) · arista-7300x3-32c (environment) · arista-7300x3-48yc4 (environment)
4.24.0 ≤ v ≤ 4.24.94.25.0 ≤ v ≤ 4.25.84.26.0 ≤ v ≤ 4.26.54.27.0 ≤ v ≤ 4.27.34.24.04.25.04.26.04.27.0
All versions
All versions
All versions
All versions
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All versions

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-284NVD-CWE-Other

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