CVE-2021-28509 | TerminAttr streams MACsec sensitive data in clear text to other authorized users in CVP

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This advisory documents the impact of an internally found vulnerability in Arista EOS state streaming telemetry agent TerminAttr and OpenConfig transport protocols. The impact of this vulnerability is that, in certain conditions, TerminAttr might leak MACsec sensitive data in clear text in CVP to other authorized users, which could cause MACsec traffic to be decrypted or modified by other authorized users on the device.

Published: 2022-05-26 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-28509 is rated Exploit Available (51.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.44%). 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-2021-28509

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

Exploit prediction scoring system (EPSS) score for CVE-2021-28509

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 0.14% 0.44% +0.30%
2 2025-06-11 0.16% 0.14% -0.02%
3 2025-06-01 — 0.16% —

Full EPSS history (5 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-28509

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N 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:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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:N)
Service keeps running; no real outage angle.
 0.9 5.2 [email protected]
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N 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:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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:N)
Service keeps running; no real outage angle.
 0.9 5.2 [email protected]
3.6 2.0 LOW
AV:N/AC:H/Au:S/C:P/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:H)
Exploitation requires uncommon or highly specific conditions.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 3.9 4.9 [email protected]

Weakness enumeration for CVE-2021-28509

Affected software / configurations for CVE-2021-28509

Vendor Product Version Raw CPE
arista terminattr < 1.10.11 cpe:2.3:a:arista:terminattr:*:*:*:*:*:*:*:*
arista terminattr >= 1.11.0, < 1.16.8 cpe:2.3:a:arista:terminattr:*:*:*:*:*:*:*:*
arista terminattr >= 1.17.0, < 1.19.2 cpe:2.3:a:arista:terminattr:*:*:*:*:*:*:*:*
arista eos >= 4.23, <= 4.23.11 cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.24, < 4.24.10 cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.25, < 4.25.8 cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.26, < 4.26.6 cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*
arista eos >= 4.27, < 4.27.4 cpe:2.3:o:arista:eos:*:*:*:*:*:*:*:*

References for CVE-2021-28509

cvelogic Threat Intelligence