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NVD / CVE Program· CNA Arista

CVE-2021-28505: 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…

HighCVSS 7.5 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Monitor (action score 30/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.88% (FIRST EPSS); higher than 59.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published
Apr 14, 2022
Updated
Jun 16, 2026
EPSS
0.8% · 59th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CNA vs NVD score

NVD
7.5
CNA · Arista
7.5
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-28505

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
aristaeos
aristaccs-710p-12
aristaccs-710p-16p
aristaccs-720xp-24y6
aristaccs-720xp-24zy4
aristaccs-720xp-48y6
aristaccs-720xp-48zc2
aristaccs-720xp-96zc2
aristaccs-722xpm-48y4
aristaccs-722xpm-48zy8
aristadcs-7010tx-48
aristadcs-7050cx3-32s

and 6 more

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Arista). Independent of NVD's CPE analysis and usually ahead of it.

  • Arista Networks EOS

    • 4.26.3M and later · up to and including 4.26.0affected
    • 4.27.0F and later · up to and including 4.27.0affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • arista eos4.26 and later · before 4.26.4m
  • arista eos4.27 and later · before 4.27.1f

Same product

arista: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-7473Arista EOS Unexpected Tunnel Protocol Decapsulation and Forwarding BypassKEV
    60This week
  • CVE-2015-8236Arista EOS before 4.11.12, 4.12 before 4.12.11, 4.13 before 4.13.14M, 4.14 before 4.14.5FX.5, and 4.15 before 4.15.0FX1.1 allows remote…
    41Plan
  • CVE-2021-28503In Arista's EOS software affected releases, eAPI might skip re-evaluating user credentials when certificate based authentication is used, which allows remote…
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2021-28507Jan 14, 2022 · An issue has recently been discovered in Arista EOS where, under certain conditions, the service ACL configured for OpenConfig gNOI and OpenConfig RESTCONF…
    28Monitor
  • ← EarlierCVE-2021-28504Apr 1, 2022 · On Arista Strata family products which have “TCAM profile” feature enabled when Port IPv4 access-list has a rule which matches on “vxlan” as protocol then that…
    30Monitor
  • Later →CVE-2021-28511Aug 5, 2022 · 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…
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-284 · Improper Access Control

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

All records