CVE-2021-28500 | An issue has recently been discovered in Arista EOS where the incorrect use of EOS's AAA API’s by the OpenConfig and TerminAttr agents could result in unrestricted access to the device for local users with nopassword configuration.

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An issue has recently been discovered in Arista EOS where the incorrect use of EOS's AAA API’s by the OpenConfig and TerminAttr agents could result in unrestricted access to the device for local users with nopassword configuration.

Published: 2022-01-14 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-28500 is rated High Exploit Risk (70.8/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 0.87%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-28500

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-28500

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.29% 0.87% +0.58%
2 2025-11-21 0.14% 0.29% +0.15%
3 2025-11-18 — 0.14% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-28500

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.2 [email protected]
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 [email protected]
6.9 2.0 MEDIUM
AV:L/AC:M/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.4 10.0 [email protected]

Weakness enumeration for CVE-2021-28500

Affected software / configurations for CVE-2021-28500

Vendor Product Version Raw CPE
arista eos < 4.20 cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.21.0, <= 4.21.14m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.22.0, <= 4.22.11m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.23.0, <= 4.23.8m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.24.6.0, <= 4.24.6m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.25.0, <= 4.25.4m cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.26.0, <= 4.26.1f cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*

References for CVE-2021-28500

cvelogic Threat Intelligence