CVE-2021-28497

Unauthorized Bash shell access for low-privileged users

Published Sep 9, 2021 · Updated Aug 3, 2024

Improper access control in Arista Networks MOS allows local users to obtain an unintended Bash shell on affected 7130 systems. Arista has not disclosed which login or privilege-transition path incorrectly launches Bash for an unprivileged account. Exploitation requires existing low-privileged local access and permits shell commands beyond the account's intended authorization on all MOS-0.1x releases, MOS-0.26.6 and earlier in the 0.2x train, and MOS-0.31.1 and earlier in the 0.3x train.

CVSS severity4.4
Medium
EPSS probability0.23%
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 Networks MOS allows local users to obtain an unintended Bash shell on affected 7130 systems. Arista has not disclosed which login or privilege-transition path incorrectly launches Bash for an unprivileged account. Exploitation requires existing low-privileged local access and permits shell commands beyond the account's intended authorization on all MOS-0.1x releases, MOS-0.26.6 and earlier in the 0.2x train, and MOS-0.31.1 and earlier in the 0.3x train.

The record

CVE
CVE-2021-28497
Published
Sep 9, 2021
Updated
Aug 3, 2024
Vendor
Arista Networks
Product
MOS (Metamako Operating System)
Classifications
CWE-264, T1059.004
Attack vector
local
Privileges
authenticated

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-0.26.7 <MOS-0.16.7
  2. Affected versionversion=MOS-0.32.0 <MOS-0.32.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Arista Networks · MOS (Metamako Operating System)version=MOS-0.26.7 <MOS-0.16.7; version=MOS-0.32.0 <MOS-0.32.0

Published CVSS scores

4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
4.4Arista Networks, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-264Permissions, Privileges, and Access Controls
T1059.004Command and Scripting Interpreter: Unix Shell

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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