CVE-2021-28495Network attack vector

Unauthenticated JSON-RPC access via undisclosed authentication flaw

Published Sep 9, 2021 · Updated Aug 3, 2024

Authentication bypass in Arista Networks MOS allows remote attackers to access enabled JSON-RPC APIs without valid credentials. Arista has not published the specific authentication check or request-processing error that accepts unauthenticated JSON-RPC calls. The JSON API server must be enabled; successful exploitation can alter data or interrupt service, but the vendor reports no confidentiality impact.

CVSS severity7.2
High
EPSS probability0.93%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Arista Networks MOS allows remote attackers to access enabled JSON-RPC APIs without valid credentials. Arista has not published the specific authentication check or request-processing error that accepts unauthenticated JSON-RPC calls. The JSON API server must be enabled; successful exploitation can alter data or interrupt service, but the vendor reports no confidentiality impact.

The record

CVE
CVE-2021-28495
Published
Sep 9, 2021
Updated
Aug 3, 2024
Vendor
Arista Networks
Product
MOS (Metamako Operating System)
Classifications
CWE-287, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=MOS-0.13 <MOS-0.13*
  2. Affected versionversion=MOS-0.26.7 <MOS-0.26.7
  3. Affected versionversion=MOS-0.32.0 <MOS-0.32.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Arista Networks · MOS (Metamako Operating System)version=MOS-0.13 <MOS-0.13*; version=MOS-0.26.7 <MOS-0.26.7; version=MOS-0.32.0 <MOS-0.32.0

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.2Arista NetworksCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1210Exploitation of Remote Services

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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