CVE-2021-28507Network attack vector

Service ACL bypass via forwarded denied requests

Published Jan 14, 2022 · Updated Sep 17, 2024

Improper access control in Arista EOS allows remote authenticated users to bypass OpenConfig gNOI and RESTCONF service ACLs. When a service ACL is attached to either transport, denied requests are forwarded to the corresponding agent instead of being rejected. Exploitation requires a configured service ACL and high-privilege authentication, enabling agent operations that the source-address policy denies.

CVSS severity5.5
Medium
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Arista EOS allows remote authenticated users to bypass OpenConfig gNOI and RESTCONF service ACLs. When a service ACL is attached to either transport, denied requests are forwarded to the corresponding agent instead of being rejected. Exploitation requires a configured service ACL and high-privilege authentication, enabling agent operations that the source-address policy denies.

The record

CVE
CVE-2021-28507
Published
Jan 14, 2022
Updated
Sep 17, 2024
Vendor
Arista Networks
Product
Arista EOS
Classifications
CWE-284, T1190
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jan 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.21.x <=4.21.x
  2. Affected versionversion=4.22.x
  3. Affected versionversion=4.23.9M <=4.23.0
  4. Affected versionversion=4.24.7M <=4.24.0
  5. Affected versionversion=4.25.3 <=4.25.0
  6. Affected versionversion=4.25.4M <=4.25.4
  7. Affected versionversion=4.25.5.1M <=4.25.5
  8. Affected versionversion=4.26.2F <=4.26.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Arista Networks · Arista EOSversion=4.21.x <=4.21.x; version=4.22.x; version=4.23.9M <=4.23.0; version=4.24.7M <=4.24.0; version=4.25.3 <=4.25.0; version=4.25.4M <=4.25.4; version=4.25.5.1M <=4.25.5; version=4.26.2F <=4.26.0

Published CVSS scores

4.9NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:N
7.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
5.5Arista Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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